Index: /CKEditor/trunk/CHANGES.html
===================================================================
--- /CKEditor/trunk/CHANGES.html	(revision 5740)
+++ /CKEditor/trunk/CHANGES.html	(revision 5741)
@@ -90,4 +90,5 @@
 		<li><a href="http://dev.fckeditor.net/ticket/5338">#5338</a> : Pasting from Open Office could lead on error.</li>
 		<li><a href="http://dev.fckeditor.net/ticket/5224">#5224</a> : Some invalid markup could break the editor.</li>
+		<li><a href="http://dev.fckeditor.net/ticket/5455">#5455</a> : It was not possible to remove formatting from pasted content on specific cases.</li>
 		<li>Updated the following language files:<ul>
 			<li><a href="http://dev.fckeditor.net/ticket/5962">#5962</a> : German;</li>
Index: /CKEditor/trunk/_source/core/dom/element.js
===================================================================
--- /CKEditor/trunk/_source/core/dom/element.js	(revision 5740)
+++ /CKEditor/trunk/_source/core/dom/element.js	(revision 5741)
@@ -851,6 +851,14 @@
 				function()
 				{
-					var attributes = this.$.attributes;
-					return ( attributes.length > 1 || ( attributes.length == 1 && attributes[0].nodeName != '_cke_expando' ) );
+					var attrs = this.$.attributes,
+						attrsNum = attrs.length;
+
+					// The _moz_dirty attribute might get into the element after pasting (#5455)
+					var execludeAttrs = { _cke_expando : 1, _moz_dirty : 1 };
+
+					return attrsNum > 0 &&
+						( attrsNum > 2 ||
+							!execludeAttrs[ attrs[0].nodeName ] ||
+							( attrsNum == 2 && !execludeAttrs[ attrs[1].nodeName ] ) );
 				},