conq writes "BusinessWeek explores yet another click fraud scam, this one utilizing Yahoo!'s ads." From the article: "Somewhere along the way, an ad can wander off this trail. This happens when one of Yahoo's partners decides to give its own partners a cut in return for traffic, Edelman says. According to the study, a Yahoo partner called Ditto.com served an Overture advertisement through another site, NBCSearch (no affiliation with General Electric's NBC), unaffiliated with Yahoo. That company, in turn, passed it along to one of its own partners. (NBCSearch didn't immediately respond to requests for comment.) When that happens, Yahoo can't track its ads. Sometimes, the ads show up in undesirable places, like a pop-up from a spyware program. The average user simply sees the pop-up, unaware of how many networks it traversed beforehand."