A ClickDefense executive pegged the proportion at 70 percent of bad clicks. CEO Scott Boyenger said that 15 to 20 percent of all clicks are fraudulent. "The advertiser is the loser and the companies offering PPC are winning, and so are the affiliates." Fathom Online's Matt McMahon agreed that the offending parties were generally affiliates, but said that the problem would likely work itself out as advertisers left programs that had poor returns due to fraud." Panelists at the recent Search Engine Strategies conference tended to agree that second- and third-tier search engines - those other than Google or Overture - tended to have higher rates of click fraud.

4 Mar 2005

http://www.marketingvox.com/archives/2005/03/04/search_execs_blame_affiliates_point_to_2ndtier_engines_for_click_fraud/index.php