Given that most of Google’s $13 billion in revenue comes from clicks on ads, you would think the words “click fraud” would inspire fear in Shuman Ghosemajumder, the company’s senior product manager and resident click-fraud czar. But the problem–publishers who inflate pay-per-click ad fees with automatic clicking software–doesn’t fluster Ghosemajumder or other Googlers.In March 2006, as the company faced a class-action lawsuit from online advertisers for damages from fraudulent clicks, Google Chief Executive Eric Schmidt dismissed click fraud as “immaterial.” Even after paying a $90 million settlement, Google has maintained its “everything-is-just-fine” answer to click-fraud worrywarts.Not all outsiders are reassured. A report in July from Click Forensics, an Austin, Texas-based click-fraud auditing firm, contended that click fraud is growing, particularly on content networks like Google Adsense and Yahoo Publisher Network. The report, drawn from more than 4,000 sites’ advertising data, asserted that the rate of fraudulent clicks was 15.8% in the second quarter of 2007, up 1% from three months earlier. Within online content networks, Click Forensics estimated that more than 25% of all clicks were fraudulent, up from about 22% percent in the previous quarter.Ghosemajumder doesn’t buy it. He spoke with Forbes.com about why some third-party auditors overestimate malicious clicks, the myth that Google profits from click fraud and just how the company can reassure advertisers without giving away the secrets of its click-fraud detection.For the Forbes interview with Shuman Ghosemajumder, see http://www.forbes.com/technology/2007/09/13/google-shuman-fraud-tech-cx_ag_0914google.html