I am noticing a lot of people in the various Adsense forums complaining about a low CPC. I have been advising people to consider using Google's competitive ad filter to try and improve their payouts. I haven't used the tool much myself, and after a good day yesterday today I received two clicks paying out just $0.32. Something isn't right here, time to follow my own advice. http://forums.digitalpoint.com/showthread.php?t=178506 Read this great post by Manthem. I think everyone should take his advice and act on it now. Forget the ads blacklist, that won't help if you have a specific niche. You need to observe your own ads and conduct your own research. I noticed a fairly common and prominent ad of mine a few days ago and thought nothing of it. Today, after doing a little research, I discovered that the website it is advertising needs it's domain renewed! It expired a few days ago. This surely must affect the ads CPC and therefore is affecting my earnings. I've now added the site to my ad filter and hopefully I'll benefit in the next few hours. I believe with thorough research you can definitely improve your CPC regardless of your niche. If you're noticing strange clicks that aren't paying much or your CPC seems to fluctuates a hell of a lot, start observing your ads and maximize your earnings.
Here, here. Fully agree. Nothing beats your own research. The blacklist is only a reference of known problem ads and shouldn't be relied on 100%. You can be site targeted by people not on that list and you'd never know without researching the ads.
The only problem with doing your own research is geo-targeting. You only see the ads on your site which are local to you, and other people elsewhere will see completely different adverts. The official AdSense Preview Tool lets you choose which geographic location to use when viewing the ads. Cryo.