When i checked the number of "supposid" clicks i was getting with my actual logs i found that for some sites i was only getting 10% of what was being reported in google, for a few sites it was close to 80%. On average i recieved 60% of what google said i should get. Keep in mind my stats are in real time and the google stats are a few hours delayed. I suspect i'm getting about 40% of the traffic that google says i'm getting.
I suspect google google has turned off fraud detection for CPM ads and now we can see how truely wide spread it is.