The Fool has a commentary by Seth Jayson discussing, among other thing, the impact of click fraud:
Whether or not you believe that the junk sites out there peddling AdSense ads are honest commerce or capitalizing on large-scale click fraud, there’s little doubt in my mind that we’ve got Google to thank for it. There’s simply no reason for people to set up these sites if they can’t skim dough via third-hand revenue sharing enabled by Google’s business model. With Yahoo! and others set to get in on the same gig, I don’t think we’ll see this trend abate.
I think that bodes for a return to the old days — that the blogosphere that’s being so rapidly diluted and co-opted by these AdSense shenanigans will become a lot less important. As a result, trusted information providers — and some will doubtlessly be blogs — will become more important. As they realize the power of their information, they’ll be a lot less willing to allow Google to skim dollars off the content and reputation they’ve worked to build.
Moreover, targeted, structured data behind the scenes will be the new source of high-worth information, which means that businesses will be a lot more interested in the user-generated recommendations that Netflix (Nasdaq: NFLX) and eBay (Nasdaq: EBAY) offer their millions of customers. That’ll be a lot more useful than what Google knows about 5,000 boy-crazy girls on MySpace or Blogspot who’ve been trading reviews on Justin’s latest single.