Despite Google's assertions otherwise, most projections of the percentage of click fraud incidences are pretty honest. Though they are just "projections," what all the projections do agree on is this: no one can really knows the extent of click fraud, but it could be more than the ten to fifteen percent; it could be as high as twenty percent, and it could be as low as the nine percent "detected invalid click rate" that Google's Shuman Ghosemajumdar presented to bloggers and search analysts on December 2006.
Real fraud is never discovered (once discovered, it is no longer effective). Click fraudsters would pay anything not to be discovered, and hence continue in their activities. Botmasters are willing to rent out several hundred machines to click fraud networks. Estimates so far from Georgia Tech College of Computing, which conducts extensive research in viruses, malware and bots in computing say as much as seven percent (ten million to twelve million PCs) of the computers connected to the Internet are unwitting zombie computers, and a few hundred thousand are added every week.
Fully automated spam is a more lucrative (or more widespread) business than automated click fraud. Reported cases of zombie computers have them sending spam. Georgia Tech and a few other security experts, however, noted increased cases of bots being used for click fraud. They have tracked the means of propagation and even in some cases discovered the botmaster's URL; see here and here.
Threatening the Foundation of the Internet
Pay per click is the biggest form of online advertising currently. Money spent on online advertising is going to more than triple in the next four years (according to forecasts by Piper Jaffray). The bad press on click fraud initially came from the print press, leading to speculation that it was simply an attack from a dying media (print) on a new and vibrant one (the Internet). While that is possible, it is by far an exaggeration. Print media is adapting, and so is television and radio. Google is still moaning about bad press, but most of the reporting on click fraud now is from web-based news sites, who are again purported to have a vested interest.
The reason the search engines (and publishers too!) are downplaying the click fraud issue is because it could destroy the whole basis of Internet advertising as we know it. The chain of interests that would love for the "click fraud" problem to continue is long: Internet publishers, venture capitalist companies who invest in these web sites, the search engines, and others.
The problem could very well be minor for all we know, but if the number of black hats on the Internet is anything to go by, the problem will increase and become more obvious as time goes on and online advertising revenue increases. We could see incidences and reactions to click fraud becoming as bad as current incidences and reactions to spam.
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