One 'trick' that adsense publishers use to increase their CPC rates (cost per click) is to use the competitive filter feature of adsense to block of low-paying "Made for Adsense" sites.
"Made for Adsense" a.k.a. MFA are specially made sites for purpose of displaying google ads and gaining revenue by sending traffic using AdWords. They buy from Adwords then make money from adsense. It is kinda like "Buy low, sell high" strategy.
You've probably seen google ads with text like "best products for ...", or "Best info about ...". These advertisers usually pay only between $0.01 to $0.05 per click. The idea is to to eliminate those sites from showing in your adsense ads.
Detecting them is quite simple. If you see more ads than content, then that's a very likely candidate. Another is if you see scraped content.
There's an ongoing free project called adsblacklist.com whose purpose is to consolidate adsense publishers' list of MFA sites that they use in their competitive filter. It is more of a sharing of info between members. Try using that and take a look what happens. Drop me a note if you see an increase in your income.
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