Impression Spam Worries Google Advertisers

Google is on the lookout for “impression spam” but denies it poses a big threat to paid search advertisers. Advertisers and SEM firms beg to differ.

The search engine giant defines impression spam as “ad impressions generated outside of normal search activity, in some cases deliberate in other cases not deliberate,” whose overall effect is minimal, said Salar Kamangar, Google’s director of product management.

Paid search advertisers like Richard Leino, the founder of, disagree about the “minimal” part. Because Google takes click-through-rate (CTR) into account when it decides the rankings of search ads, extra impressions without click-throughs can result in an ad being demoted or even disabled. (Overture does not use CTRs to determine the ranking of its paid search listings.)

Advertising on “Web hosting” was Leino’s introduction to the effects of impression spam. In the last 10 months, Leino periodically noticed bursts of ad impressions over 10 times higher than the typical daily average on the keyword.

“I’ve seen acts of God, hurricanes on the keyword, with over 100,000 impressions in a 12-hour period on a term that typically gets 8,000 impressions a day,” Leino said.

Industry-watchers speculate fraudsters take advantage of Google’s system by disabling their own ads, making a flurry of queries on their chosen keywords, and then re-enabling their ads. By doing this, they drive down the CTR on competitors’ listings, then swoop back in to claim higher rankings.

“I’ve had consistently good click-through rates for the last 10 months, but periodically you see all your efforts get wiped out in a matter of hours, and you have to increase your cost per click to get back on top,” Leino said.

Leino estimates impression spam has cost him a total of $1,000 to $2,000 in the last 10 months, because he had to pay more to keep a higher ranking and potentially lost business when his ad ranking went down. That amounts to between five and 10 percent of his total revenues during that time period.

Google has gotten increasingly vigilant about dealing with Leino’s impression spam problem, he said.

“Google initially told me there was nothing that could be done about it, but a few months later did erase the false impressions, which improved my click-through rate,” Leino said. “The problem is it keeps occurring.”

For Lisa Wehr, president of SEM firm Oneupweb, incidents of impression spam like the one Leino experienced call into question the logic of Google’s CTR-based ad-ranking system.

“It’s further evidence that if there is a chink in the armor, it will be exploited,” Wehr said. “This is where Google needs to review what they’re doing. Without the CTR algorithm, impression spam would go away.”

But Kamangar defended the value created by its CTR-based ad ranking system for both search engine users and advertisers. “Our ad ranking system ensures that the most relevant ads will be seen by the users of our search engine,” he said. “It’s good for advertisers because it prevents advertisers from dominating a narrow field simply by paying a higher cost per click.”

Gauging the prevalence of impression spam is another thorny problem, said Gordon Brott, VP of marketing for WhosClickingWho, a business that identifies and stops click fraud.

“As far as we can tell, impression spam is not nearly as widespread as click fraud,” Brott said. “But it’s probably safe to say that the problem is going to get bigger.”

Google, however, doesn’t expect incidents of impression spam to escalate, Google’s Kamangar said.

“We have an automated system in place that detects when unusual amounts of impressions are occurring without click-throughs,” Kamangar said. “And we have a team of analysts in place to research cases that are reported to us. It’s a mechanism that grows more sophisticated over time and one that is working. So we do not expect an increase in the number of incidents in the future.”

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