Two sites Site #1 - One had content related to web hosting.. Site #2 - One had no content.. and was new.. I started working on both sites with almost similar content. The new content was less paying than "web hosting". Both sites became popular. Site #2 got more traffic however CPC was less than Site #1 At first I was not able to figure it out however.. Adsense showed web hosting ads sometimes on site #1.. even though content now was different and as web hosting keyword pay good.. I got higher CPC.. So here is deal.. Post High Paying Content on your websites first and leave it there for a while like a month.. Then Post any random content.. and your CPC will be good.
neah...I disagree . Google Adsense will smell this from a mile . Ads will change when you will change the content.. there must be another reason ....keeep searching