It seems that the Fair Isaac Corporation released this study saying that 10-15% of all billable clicks at Google were fraudulent. It seems that right after this announcement was made Google started going on the ban spree. You can read more about it on my blog here Really puts things into perspective when you think that at one time they "respected" arbitrage as a business model and now they are saying they dont like the way you do business anymore. Definitely not "not evil" if you ask me. Whaddya think?
If you use AdWords, you would know that Google's content network is loaded with MFA sites. They need to clean that up if they want to keep quality advertisers.