Sure. It should be pointed out that it is much easier to commit click fraud than to defraud charging of other types of media. It doesn't even require any particular expertise; it can just be carried out by a group of individuals who agree to click on some sites here and there. They don't even need to make money off of the fraud; they can just do it to pump up the spend of an advertiser they want to harass.
Anyway, I'm just pointing out some things that I've learned in the hopes that others will find them useful. If someone can make money off of CPC despite click fraud, more power to them. I still think it is a bad idea in general. I don't think I could in all conscience recommend it as a hallmark of commerce.