Not so many years back, a friend of mine was running multiple campaigns and had figured out a glitch in Google Adwords to get tens of thousands of dollars in free PPC and radio ads. I mean seriously he raked in something like $150,000. in radio ads for one of our websites and about fifty K in PPC for a few of our websites, without anyone's having to pay for it. Google has tightened up now, and the radio is gone, but still it's easy to get something like a few thousand dollars free PPC per account easily. Seems like Google is not worried about giving away for free to those who know how to exploit it. And I'll add that the way he was doing this not one of our websites ever got black listed by Google, and our legitimate paying Adwords campaigns on different accounts to these same websites stayed in place and are still running fine to this day. But why pay when can get for free?