The number of advertiser accounts suspended by Google exploded last year. In 2010 Google ended 248,000 advertising accounts for terms of service and advertising policy violations. Nearly four times as many accounts were suspended in 2011 - 824,000.

In 2010 Google denied a total of 56.7 million ads, and that number more than doubled to 134 million ads killed in 2011.

Google said it has worked to improve its systems and utilize new techniques to prevent so-called bad ads from running on its properties and ad network over the last few years. The firm has put in place policies that do not allow ads containing misleading claims, spam or malware. ...