diff --git a/src/css/devtool-log.css b/src/css/devtool-log.css
index 76ad1be36..d9d2f7f8d 100644
--- a/src/css/devtool-log.css
+++ b/src/css/devtool-log.css
@@ -70,6 +70,9 @@ body.colorBlind #content table tr.allowed {
 #content table tr.maindoc {
     background-color: #eee;
     }
+#content table tr.cosmetic {
+    background-color: rgba(255, 255, 0, 0.1)
+    }
 body:not(.filterOff) #content table tr.hidden {
     display: none;
     }
diff --git a/src/js/contentscript-end.js b/src/js/contentscript-end.js
index 2c394605a..ed2888060 100644
--- a/src/js/contentscript-end.js
+++ b/src/js/contentscript-end.js
@@ -169,7 +169,7 @@ var uBlockCollapser = (function() {
         }
         if ( selectors.length !== 0 ) {
             messager.send({
-                what: 'injectedSelectors',
+                what: 'cosmeticFiltersInjected',
                 type: 'net',
                 hostname: window.location.hostname,
                 selectors: selectors
@@ -385,7 +385,7 @@ var uBlockCollapser = (function() {
     // - Injecting a style tag
 
     var addStyleTag = function(selectors) {
-        var selectorStr = selectors.toString();
+        var selectorStr = selectors.join(',\n');
         var style = document.createElement('style');
         // The linefeed before the style block is very important: do no remove!
         style.appendChild(document.createTextNode(selectorStr + '\n{display:none !important;}'));
@@ -396,7 +396,7 @@ var uBlockCollapser = (function() {
         }
         hideElements(selectorStr);
         messager.send({
-            what: 'injectedSelectors',
+            what: 'cosmeticFiltersInjected',
             type: 'cosmetic',
             hostname: window.location.hostname,
             selectors: selectors
diff --git a/src/js/contentscript-start.js b/src/js/contentscript-start.js
index a7f7cbbfa..8bdc80cab 100644
--- a/src/js/contentscript-start.js
+++ b/src/js/contentscript-start.js
@@ -123,6 +123,8 @@ var netFilters = function(details) {
 };
 
 var filteringHandler = function(details) {
+    var styleTagCount = vAPI.styles.length;
+
     vAPI.skipCosmeticFiltering = !details || details.skipCosmeticFiltering;
     if ( details ) {
         if ( details.cosmeticHide.length !== 0 || details.cosmeticDonthide.length !== 0 ) {
@@ -135,6 +137,12 @@ var filteringHandler = function(details) {
         // the browser to flush this script from memory.
     }
 
+    // This is just to inform the background process that cosmetic filters were
+    // actually injected.
+    if ( vAPI.styles.length !== styleTagCount ) {
+        localMessager.send({ what: 'cosmeticFiltersInjected' });
+    }
+
     // https://github.com/chrisaljoudi/uBlock/issues/587
     // If no filters were found, maybe the script was injected before uBlock's
     // process was fully initialized. When this happens, pages won't be
diff --git a/src/js/cosmetic-logger.js b/src/js/cosmetic-logger.js
new file mode 100644
index 000000000..f2c9f82e4
--- /dev/null
+++ b/src/js/cosmetic-logger.js
@@ -0,0 +1,96 @@
+/*******************************************************************************
+
+    uBlock - a browser extension to block requests.
+    Copyright (C) 2015 Raymond Hill
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see {http://www.gnu.org/licenses/}.
+
+    Home: https://github.com/gorhill/uBlock
+*/
+
+/* global vAPI, HTMLDocument */
+
+/******************************************************************************/
+
+(function() {
+
+'use strict';
+
+/******************************************************************************/
+
+// https://github.com/gorhill/uBlock/issues/464
+if ( document instanceof HTMLDocument === false ) {
+    //console.debug('cosmetic-logger.js > not a HTLMDocument');
+    return;
+}
+
+// This can happen
+if ( !vAPI ) {
+    //console.debug('cosmetic-logger.js > vAPI not found');
+    return;
+}
+
+/******************************************************************************/
+
+var loggedSelectors = vAPI.loggedSelectors || {};
+
+var injectedSelectors = [];
+var reProperties = /\s*\{[^}]+\}\s*/;
+var i;
+var styles = vAPI.styles || [];
+
+i = styles.length;
+while ( i-- ) {
+    injectedSelectors = injectedSelectors.concat(styles[i].textContent.replace(reProperties, '').split(/\s*,\n\s*/));
+}
+
+if ( injectedSelectors.length === 0 ) {
+    return;
+}
+
+var matchedSelectors = [];
+var selector;
+
+i = injectedSelectors.length;
+while ( i-- ) {
+    selector = injectedSelectors[i];
+    if ( loggedSelectors.hasOwnProperty(selector) ) {
+        continue;
+    }
+    loggedSelectors[selector] = true;
+    if ( document.querySelector(selector) === null ) {
+        continue;
+    }
+    matchedSelectors.push(selector);
+}
+
+vAPI.loggedSelectors = loggedSelectors;
+
+/******************************************************************************/
+
+var localMessager = vAPI.messaging.channel('cosmetic-*.js');
+
+localMessager.send({
+    what: 'logCosmeticFilteringData',
+    pageURL: window.location.href,
+    matchedSelectors: matchedSelectors
+}, function() {
+    localMessager.close();
+});
+
+/******************************************************************************/
+
+})();
+
+/******************************************************************************/
diff --git a/src/js/cosmetic-count.js b/src/js/cosmetic-survey.js
similarity index 76%
rename from src/js/cosmetic-count.js
rename to src/js/cosmetic-survey.js
index 3dcee09ce..532bf9b65 100644
--- a/src/js/cosmetic-count.js
+++ b/src/js/cosmetic-survey.js
@@ -31,13 +31,13 @@
 
 // https://github.com/gorhill/uBlock/issues/464
 if ( document instanceof HTMLDocument === false ) {
-    //console.debug('cosmetic-on.js > not a HTLMDocument');
+    //console.debug('cosmetic-survey.js > not a HTLMDocument');
     return;
 }
 
 // This can happen
 if ( !vAPI ) {
-    //console.debug('cosmetic-count.js > no vAPI');
+    //console.debug('cosmetic-survey.js > vAPI not found');
     return;
 }
 
@@ -45,23 +45,20 @@ if ( !vAPI ) {
 
 // Insert all cosmetic filtering-related style tags in the DOM
 
-var selectors = [];
+var injectedSelectors = [];
+var filteredElementCount = 0;
+
 var reProperties = /\s*\{[^}]+\}\s*/;
 var i;
 
 var styles = vAPI.styles || [];
 i = styles.length;
 while ( i-- ) {
-    selectors.push(styles[i].textContent.replace(reProperties, ''));
+    injectedSelectors = injectedSelectors.concat(styles[i].textContent.replace(reProperties, '').split(/\s*,\n\s*/));
 }
 
-var elems = [];
-
-if ( selectors.length !== 0 ) {
-    try {
-        elems = document.querySelectorAll(selectors.join(','));
-    } catch (e) {
-    }
+if ( injectedSelectors.length !== 0 ) {
+    filteredElementCount = document.querySelectorAll(injectedSelectors.join(',')).length;
 }
 
 /******************************************************************************/
@@ -69,8 +66,10 @@ if ( selectors.length !== 0 ) {
 var localMessager = vAPI.messaging.channel('cosmetic-*.js');
 
 localMessager.send({
-    what: 'hiddenElementCount',
-    count: elems.length
+    what: 'liveCosmeticFilteringData',
+    pageURL: window.location.href,
+    filteredElementCount: filteredElementCount,
+    injectedSelectors: injectedSelectors
 }, function() {
     localMessager.close();
 });
diff --git a/src/js/devtool-log.js b/src/js/devtool-log.js
index 5862beb48..e2e78e78a 100644
--- a/src/js/devtool-log.js
+++ b/src/js/devtool-log.js
@@ -123,6 +123,12 @@ var createRow = function() {
 
 var renderLogEntry = function(entry) {
     var tr = createRow();
+
+    // Cosmetic filter?
+    if ( entry.result.charAt(0) === 'c' ) {
+        tr.classList.add('cosmetic');
+    }
+
     if ( entry.result.charAt(1) === 'b' ) {
         tr.classList.add('blocked');
         tr.cells[0].textContent = ' -\u00A0';
@@ -135,13 +141,16 @@ var renderLogEntry = function(entry) {
     } else {
         tr.cells[0].textContent = '';
     }
+
     if ( entry.type === 'main_frame' ) {
         tr.classList.add('maindoc');
     }
+
     var filterText = entry.result.slice(3);
     if ( entry.result.lastIndexOf('sa', 0) === 0 ) {
         filterText = '@@' + filterText;
     }
+
     tr.cells[1].textContent = filterText + '\t';
     tr.cells[2].textContent = (prettyRequestTypes[entry.type] || entry.type) + '\t';
     vAPI.insertHTML(tr.cells[3], renderURL(entry.url, entry.result));
diff --git a/src/js/logger.js b/src/js/logger.js
index eb77e0765..dc9e3a3c8 100644
--- a/src/js/logger.js
+++ b/src/js/logger.js
@@ -152,7 +152,7 @@ var logBufferObsoleteAfter = 30 * 1000;
 
 /******************************************************************************/
 
-var loggerWriteOne = function(tabId, details, result) {
+var writeOne = function(tabId, details, result) {
     if ( logBuffers.hasOwnProperty(tabId) === false ) {
         return;
     }
@@ -162,7 +162,7 @@ var loggerWriteOne = function(tabId, details, result) {
 
 /******************************************************************************/
 
-var loggerReadAll = function(tabId) {
+var readAll = function(tabId) {
     if ( logBuffers.hasOwnProperty(tabId) === false ) {
         logBuffers[tabId] = new LogBuffer();
     }
@@ -171,6 +171,12 @@ var loggerReadAll = function(tabId) {
 
 /******************************************************************************/
 
+var isObserved = function(tabId) {
+    return logBuffers.hasOwnProperty(tabId);
+};
+
+/******************************************************************************/
+
 var loggerJanitor = function() {
     var logBuffer;
     var obsolete = Date.now() - logBufferObsoleteAfter;
@@ -195,8 +201,9 @@ setTimeout(loggerJanitor, loggerJanitorPeriod);
 /******************************************************************************/
 
 return {
-    writeOne: loggerWriteOne,
-    readAll: loggerReadAll
+    writeOne: writeOne,
+    readAll: readAll,
+    isObserved: isObserved
 };
 
 /******************************************************************************/
diff --git a/src/js/messaging.js b/src/js/messaging.js
index e880789ec..f7dcedb33 100644
--- a/src/js/messaging.js
+++ b/src/js/messaging.js
@@ -37,67 +37,80 @@ var onMessage = function(request, sender, callback) {
 
     // Async
     switch ( request.what ) {
-        case 'getAssetContent':
-            // https://github.com/chrisaljoudi/uBlock/issues/417
-            µb.assets.get(request.url, callback);
-            return;
+    case 'getAssetContent':
+        // https://github.com/chrisaljoudi/uBlock/issues/417
+        µb.assets.get(request.url, callback);
+        return;
 
-        case 'reloadAllFilters':
-            µb.reloadAllFilters(callback);
-            return;
+    case 'reloadAllFilters':
+        µb.reloadAllFilters(callback);
+        return;
 
-        default:
-            break;
+    default:
+        break;
     }
 
+    var tabId = sender && sender.tab ? sender.tab.id : 0;
+
     // Sync
     var response;
 
     switch ( request.what ) {
-        case 'contextMenuEvent':
-            µb.contextMenuClientX = request.clientX;
-            µb.contextMenuClientY = request.clientY;
-            break;
+    case 'contextMenuEvent':
+        µb.contextMenuClientX = request.clientX;
+        µb.contextMenuClientY = request.clientY;
+        break;
 
-        case 'forceUpdateAssets':
-            µb.assetUpdater.force();
-            break;
+    case 'cosmeticFiltersInjected':
+        // Is this a request to cache selectors?
+        if ( Array.isArray(request.selectors) ) {
+            µb.cosmeticFilteringEngine.addToSelectorCache(request);
+        }
+        // Net-based cosmetic filters are of no interest for logging purpose.
+        if ( µb.logger.isObserved(tabId) && request.type !== 'net' ) {
+            µb.logCosmeticFilters(tabId);
+        }
+        break;
 
-        case 'getAppData':
-            response = {name: vAPI.app.name, version: vAPI.app.version};
-            break;
+    case 'forceUpdateAssets':
+        µb.assetUpdater.force();
+        break;
 
-        case 'getUserSettings':
-            response = µb.userSettings;
-            break;
+    case 'getAppData':
+        response = {name: vAPI.app.name, version: vAPI.app.version};
+        break;
 
-        case 'gotoURL':
-            vAPI.tabs.open(request.details);
-            break;
+    case 'getUserSettings':
+        response = µb.userSettings;
+        break;
 
-        case 'reloadTab':
-            if ( vAPI.isBehindTheSceneTabId(request.tabId) === false ) {
-                vAPI.tabs.reload(request.tabId);
-                if ( request.select && vAPI.tabs.select ) {
-                    vAPI.tabs.select(request.tabId);
-                }
+    case 'gotoURL':
+        vAPI.tabs.open(request.details);
+        break;
+
+    case 'reloadTab':
+        if ( vAPI.isBehindTheSceneTabId(request.tabId) === false ) {
+            vAPI.tabs.reload(request.tabId);
+            if ( request.select && vAPI.tabs.select ) {
+                vAPI.tabs.select(request.tabId);
             }
-            break;
+        }
+        break;
 
-        case 'selectFilterLists':
-            µb.selectFilterLists(request.switches);
-            break;
+    case 'selectFilterLists':
+        µb.selectFilterLists(request.switches);
+        break;
 
-        case 'toggleHostnameSwitch':
-            µb.toggleHostnameSwitch(request);
-            break;
+    case 'toggleHostnameSwitch':
+        µb.toggleHostnameSwitch(request);
+        break;
 
-        case 'userSettings':
-            response = µb.changeUserSettings(request.name, request.value);
-            break;
+    case 'userSettings':
+        response = µb.changeUserSettings(request.name, request.value);
+        break;
 
-        default:
-            return vAPI.messaging.UNHANDLED;
+    default:
+        return vAPI.messaging.UNHANDLED;
     }
 
     callback(response);
@@ -296,7 +309,7 @@ var getPopupDataLazy = function(tabId, callback) {
         return;
     }
 
-    µb.getHiddenElementCount(tabId, function() {
+    µb.surveyCosmeticFilters(tabId, function() {
         r.hiddenElementCount = pageStore.hiddenElementCount;
         callback(r);
     });
@@ -497,11 +510,11 @@ var filterRequests = function(pageStore, details) {
 
 /******************************************************************************/
 
-var onMessage = function(details, sender, callback) {
+var onMessage = function(request, sender, callback) {
     // Async
-    switch ( details.what ) {
-        default:
-            break;
+    switch ( request.what ) {
+    default:
+        break;
     }
 
     // Sync
@@ -512,33 +525,29 @@ var onMessage = function(details, sender, callback) {
         pageStore = µb.pageStoreFromTabId(sender.tab.id);
     }
 
-    switch ( details.what ) {
-        case 'retrieveGenericCosmeticSelectors':
-            response = {
-                shutdown: !pageStore || !pageStore.getNetFilteringSwitch(),
-                result: null
-            };
-            if ( !response.shutdown && pageStore.getGenericCosmeticFilteringSwitch() ) {
-                response.result = µb.cosmeticFilteringEngine.retrieveGenericSelectors(details);
-            }
-            break;
+    switch ( request.what ) {
+    case 'retrieveGenericCosmeticSelectors':
+        response = {
+            shutdown: !pageStore || !pageStore.getNetFilteringSwitch(),
+            result: null
+        };
+        if ( !response.shutdown && pageStore.getGenericCosmeticFilteringSwitch() ) {
+            response.result = µb.cosmeticFilteringEngine.retrieveGenericSelectors(request);
+        }
+        break;
 
-        case 'injectedSelectors':
-            µb.cosmeticFilteringEngine.addToSelectorCache(details);
-            break;
+    case 'filterRequests':
+        response = {
+            shutdown: !pageStore || !pageStore.getNetFilteringSwitch(),
+            result: null
+        };
+        if ( !response.shutdown ) {
+            response.result = filterRequests(pageStore, request);
+        }
+        break;
 
-        case 'filterRequests':
-            response = {
-                shutdown: !pageStore || !pageStore.getNetFilteringSwitch(),
-                result: null
-            };
-            if ( !response.shutdown ) {
-                response.result = filterRequests(pageStore, details);
-            }
-            break;
-
-        default:
-            return vAPI.messaging.UNHANDLED;
+    default:
+        return vAPI.messaging.UNHANDLED;
     }
 
     callback(response);
@@ -565,6 +574,28 @@ var µb = µBlock;
 
 /******************************************************************************/
 
+var logCosmeticFilters = function(tabId, details) {
+    if ( µb.logger.isObserved(tabId) === false ) {
+        return;
+    }
+
+    var context = {
+        requestURL: '',
+        requestHostname: µb.URI.hostnameFromURI(details.pageURL),
+        requestType: 'dom'
+    };
+
+    var selectors = details.matchedSelectors;
+
+    selectors.sort();
+
+    for ( var i = 0; i < selectors.length; i++ ) {
+        µb.logger.writeOne(tabId, context, 'cb:##' + selectors[i]);
+    }
+};
+
+/******************************************************************************/
+
 var onMessage = function(request, sender, callback) {
     // Async
     switch ( request.what ) {
@@ -575,20 +606,22 @@ var onMessage = function(request, sender, callback) {
     // Sync
     var response;
 
-    var pageStore;
-    if ( sender && sender.tab ) {
-        pageStore = µb.pageStoreFromTabId(sender.tab.id);
-    }
+    var tabId = sender && sender.tab ? sender.tab.id : 0;
 
     switch ( request.what ) {
-        case 'hiddenElementCount':
-            if ( pageStore ) {
-                pageStore.hiddenElementCount = request.count;
-            }
-            break;
+    case 'liveCosmeticFilteringData':
+        var pageStore = µb.pageStoreFromTabId(tabId);
+        if ( pageStore ) {
+            pageStore.hiddenElementCount = request.filteredElementCount;
+        }
+        break;
 
-        default:
-            return vAPI.messaging.UNHANDLED;
+    case 'logCosmeticFilteringData':
+        logCosmeticFilters(tabId, request);
+        break;
+
+    default:
+        return vAPI.messaging.UNHANDLED;
     }
 
     callback(response);
diff --git a/src/js/ublock.js b/src/js/ublock.js
index 93460227f..dfd6e81c3 100644
--- a/src/js/ublock.js
+++ b/src/js/ublock.js
@@ -338,15 +338,38 @@ var matchWhitelistDirective = function(url, hostname, directive) {
 
 /******************************************************************************/
 
-µBlock.getHiddenElementCount = function(tabId, callback) {
+µBlock.surveyCosmeticFilters = function(tabId, callback) {
     callback = callback || this.noopFunc;
     if ( vAPI.isBehindTheSceneTabId(tabId) ) {
         callback();
         return;
     }
-    vAPI.tabs.injectScript(tabId, { file: 'js/cosmetic-count.js' }, callback);
+    vAPI.tabs.injectScript(tabId, { file: 'js/cosmetic-survey.js' }, callback);
 };
 
 /******************************************************************************/
 
+µBlock.logCosmeticFilters = (function() {
+    var tabIdToTimerMap = {};
+
+    var injectNow = function(tabId) {
+        delete tabIdToTimerMap[tabId];
+        vAPI.tabs.injectScript(tabId, { file: 'js/cosmetic-logger.js' });
+    };
+
+    var injectAsync = function(tabId) {
+        if ( tabIdToTimerMap.hasOwnProperty(tabId) ) {
+            return;
+        }
+        tabIdToTimerMap[tabId] = setTimeout(
+            injectNow.bind(null, tabId),
+            100
+        );
+    };
+
+    return injectAsync;
+})();
+
+/******************************************************************************/
+
 })();