Scrapers and negligible-value-directories have been capitalizing on adsense since the start. But...I just did a google search for my own keywords and another search on my domain name (instead of clicking "Find web pages that link to" I chose "Find web pages that contain the term") and was stunned at how many of these things (euphemism for parasite) I found.

Almost none of these sites offers any user-value and few have any chance whatsoever of surfacing in serps based on pagerank, anchortext, or any other seo variable. Which leads me to suspect that the majority of clicks being generated by these sites are suspect at the very least.

It astounds me that google continues to let this crap go on. Who suffers? Presently advertisers and publishers (advertisers lowering bids due to smaller ROI). But, at some point, how can this not affect google? This is a branding problem that yahoo/overture are not indulging in themselves.