Search Engine “Impression Spam”

Click fraud has been well-discussed among SEMs/SEOs, but Rob McGann runs a good article in ClickZ calling attention to “impression spam.” This occurs because Google considers click-through rate in its sorting algorithm for paid ads. If an ad gets a low click-through rate, Google degrades placement. Thus, someone trying to game the system can generate lots of “fake” impressions, increasing the number of impressions without an increase in click-throughs, and drive down the ranking of that ad. The gamer could then take advantage of this by getting top positioning by paying a lower CPC. Google has taken some heat for its approach to click fraud; ultimately, it will need to build more game-proof systems if it wants to keep advertisers happy.