I have many sites got keyword for over 10 $ beucase of my sites do not reach the quality goals of google. Then i see this in my Adsense Tracker 7-TopSites.com 8-TopSites.com 9TopSites.com 10-BestSites.com This site are so bad and still most of my click come from them I blocked them now see if i make more or less money. How can they not pay 10 $ per keyword? There is no quality in them what so ever!
take a close look and you'll see that topsites.com and bestsites.com has a certain level 2 and level 3 content: they have links and sub links inside his sites that have some content there. is a small content but have some text there I'm not sure but this is my guess why they would not be blocked in content filter in AdWords content quality stuff.
Content and search having nothing to do with each other. The quality score only effects the search network. The fact that these kinds of sites show up in your adsense tracker is irrelevant to your quality score. They could have a bad quality score as well.
Well i do not know i know ebay have a deal with google maybe they have as well beucase if not google will close them down for sure. Maybe google use them as fillers.