I don't think they can fool Google. In the article there's patterns of clickthrough and mouseovers for both a real user and a bot. If anyone, I believe Google can detect what's likely to be a fake impression and click. It's their bread and butter.
Don't they get more bread and butter because they charge advertizers for the fraudulent clicks too and profit from them? It's not like the advertisers can ignore Ad Sense and go to a competitor easily without losing a lot of traffic.
