I was reading an inserting article about yahoo teaming up with a company that tracks click fraud and they mentioned adsense. http://www.fool.com/investing/value/2008/03/18/is-yahoo-sleeping-with-the-enemy.aspx In the end, google doesn't make that much money off its partners sites so it really doesn't care about its partners, unless your one of the larger ones.
google has millions of publishers and more people joining every day. whenever someone gets 2 clicks out of 4 impressions (50% CTR) or ads doesn;t display, or any other silly reason, they rush to send email to adsense support. its hard for google to provide individual attention to all their publishers