I was using AdSense for a few years on my websites. My account was banned out of the blue and without warning in 2012. I had over $6000 waiting to be payed. They took that away. It was within the week the payment was supposed to happen.
So I believe it. I know other webmasters that had the exact same thing happen to them too.
This is not some outlandish freak occurrence it happens all the time.
Its a hit and miss though. Nothing like what I was earning with AdSense.