Both Yahoo and Google say click fraud isn't as big of a problem as some people are saying it is and that they have ways to deal with it and are working on even better ways. Such comments can be expected since neither Google or Yahoo wants advertisers to think they are paying for fraudulent clicks.
Some click auditing companies are saying between 20 percent and 35 percent of the clicks are fraudulent. A few say it is even higher than that. Possibly the truth is somewhere between what Google and Yahoo are saying and what these click auditing companies are saying.
There is no clear standard for determining a fraudulent click. Some say it would be helpful to have an independent third-party monitor and determine it. But this would mean Google and Yahoo would give up data that could eventually reach a competitor. Google is more concerned about this than Yahoo since they have an advantage at the present time.
Of particular concern with click fraud are the sites of publishers using AdSense and Yahoo Publisher Network. Microsoft is expected to face the same problems with their MSN contextual ad network. Problems are also present with sponsored links on search engine results.
There are a lot more details about click fraud and possible ways to reduce it that will keep both the advertisers and publishers happy. This article supplies many of those details
http://news.com.com/Google+settlemen...3-6059181.html