Many years ago, I'll admit it too, I did clickfraud. I did it more to see how vulnerable the Google and OV systems were so that we could better track clickfraud in general. But the bot I had made was able to pull off a few hundred bucks in clicks, and they never caught it either. Fortunately for Google I told my manager what I had did and to refund the clicks, which she thanked me for coming clean about it, and I told them to fix certain things, which I doubt they ever did. But it just goes to show you how vulnerable and easy it is to cheat the system by doing some reverse engineering and getting some cheap but good programmers.
Is it something I would ever practice? No. Because as unethical as I may be, I hate cheaters and I'm anti-cheating and doing things illegal or things that can ultimately hurt someone.
If any of you would ever consider it, I would suggest to weigh out if it's worth the trouble and effort or not. Like when someone gets caught robbing a bank. Is it really worth stealing $30k but landing yourself in jail? No, it's not. Same with doing clickfraud. Is it worth making $10k but getting banned and possibly sued over? Definitely not. My advice is that you should NOT do it. But this is the land of the free, so it's your call. You will not get any sympathy from me if you do in fact get caught and sued.
I guess he didn't like that... 
