Automated PPC click fraud seems to be on the rise -- it doesn't take an army of paid humans clicking away, just an infected machine.
PandaLabs has detected a network of computers infected with the bot Clickbot.A, which is being used to defraud "pay per click" systems, registering clicks automatically and providing lucrative returns for the creators. According to the data collected so far, the scam is exploiting a global network comprising more than 34,000 zombie computers (those infected by the bot).
Seriously, when the lid comes off click fraud I think it will be a massive number. I've been surfing and searching on the web daily for a long time and I'm sure I haven't clicked on more than 20 or 30 ads. Anecdotal for sure but time will tell how much click fraud is out there and I'm sure its not negligible, too much $$ involved.