The commercials are hard hitting, beating up Google for everything from invasive ads in Gmail to sharing data with app developers to placing paid results on its search page. Google, the ads claim, is "Scroogling" its users, or exploiting their private data to maximize advertising profits.

And just like ruthless political attack ads, you can go nearly the full length of these without a clue as to whom is behind them. Only at the end does Microsoft identify itself. "For honest search results, try Bing," the narrator might say, sometimes waiting until the final two seconds to do so.

The Scroogled ads, negative to the core, are a rarity for consumer tech. Even the mean-spirited "I'm a Mac, I'm a PC" variety featured a product comparison at least. But while the tactics may be ugly, the ads are working, according to two ad effectiveness firms, and research commissioned by Microsoft, which finds the ads are tarnishing Google's image in the eyes of viewers and putting Microsoft products -- including underdogs such as Bing -- into the consideration set.

Effective strategy
"For Microsoft it's a win," said Jonathan Symonds, exec VP-marketing at Ace Metrix, an ad-effectiveness research firm. In Ace's evaluation, more than 53% of campaign viewers mention Google in their responses to the ads said they would look at Bing in a new light or at least seek more information. With Bing trailing Google search more than 50 percentage points at the start of the campaign, Mr. Symonds said just getting people to consider Bing over Google was a victory for Microsoft. "Microsoft will happily accept these outcomes."

Gary Getto, president of another ad-effectiveness measurement company, Advertising Benchmark Index, expressed a similar sentiment. "They have certainly raised the level of awareness of Google's activities based on the call-to-action metrics," said Mr. Getto. "People are going to talk to each other and visit the website to discuss the issue."

Once viewers do hit Scroogled.com, data collected for Microsoft by Answers Research show a 45% favorability gap in favor of Google contracting to just 5%. Data collected by Answers up until this summer also show the likelihood of someone recommending Google to a friend drop by 10%, as opposed to a 7% increase for Bing, after watching the ad.

"The "Scroogled' campaign is having a huge impact as consumers learn the stark difference between what Google says and what Google does," wrote a Microsoft spokesman in an email. Scroogled is now on its sixth wave of ads, which have been supported collectively with $10 million dollars in spending, according to a person familiar with the campaign. They also persist despite the recent revelations about the NSA's widespread surveillance activities, something Microsoft has been tied to.

"Don't think we have a comment on this one," wrote a Google spokesman.

Political tactics
Microsoft's decision to "go negative" isn't a surprise considering the man behind the initiative: Mark Penn, a political warrior and former adviser to the Clintons. Since Mr. Penn's hire, Microsoft coined "Scroogled" and has berated Google ever since. "Steve [Ballmer] asked me to provide some "out-of-the-box' thinking," said Mr. Penn. "I've helped to bring a range of new approaches -- from advertising Microsoft services together to testing the Scroogled concept, which quickly became a kind of phenomenon, as the issues raised in the campaign have gained national and international attention."

John Geer, the leader of the Vanderbilt/YouGov Ad Rating Project, which studies the effectiveness of political ads, said Microsoft's campaign is bolstered by a healthy helping of free publicity. "Mark Penn is a pretty smart guy," Mr. Geer said. "He knows if he does these negative ads, they're going to get attention in the marketplace. If they ran a positive ad, we wouldn't be having this conversation today."

Still, it's hard to say the rules of politics -- where negative ads are known to work -- apply neatly to consumer tech. The "Scroogled" ads are actually less effective than comparison ads placing the products side by side, according to Ace Metrix. Mr. Symonds said Microsoft is likely using the more negative ads to win away hardcore Google supporters and comparison ads to win over "independents." But the money appears to be better spent on the less-negative ads.

And the ads may also have the unintended impact of dragging both companies into the mud, according to Ravi Dhar, a professor of marketing and management at the Yale School of Management. "For politicians, if they attack each other, somebody is going to win, but all their ratings will go down," said Mr. Dhar. The damage to both parties, he said, will show up in the long-term data. Just look at Congress' approval ratings and you'll understand this point, Mr. Dhar said.

Microsoft, for its part, does not seem worried. When asked how long the campaign would run, a spokesman said, "The Scroogled campaign will go on as long as Google keeps Scroogling people."

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CORRECTION:An earlier version of this article cited data collected for Microsoft by GfK Roper. The data was collected by Answers Research.