Google makes the majority of its revenue from advertising, but the company is engaged in a seemingly non-stop war to ensure that so-called "scam ads" don't slip through the cracks. Just how big is the problem? Last year Google says it suspended 824,000 accounts for violating its advertising policies, and disapproved 134 million potential ads. It's a huge jump from 2010 when 248,000 accounts were suspended and 56.7 million ads weren't approved. Despite the huge growth in offending accounts and ads, Google says that there "are relatively few malicious players" that it has to deal with. But even with its apparent small size, this group appears to be nothing if not persistent. "As we get better and faster at catching these advertisers," said David W. Baker, Google's director of engineering, advertising, "they redouble their efforts and create more accounts at an even faster rate." In spite of this, Google's fight against bad ads seems to be working — back in March the company announced that the amount of offending ads displayed had been cut by 50 percent.