Google discloses that it receives payments in small print at the bottom of the shopping results page. The notice is also visible if a user clicks on a link at the top of the shopping results page, under the heading: "Why these products?"
What's left unsaid is the omission of sites such as Amazon, which tends to offer some of the best deals on the Web.
The financially driven system for determining the results in a major part of Google's search engine breaks new ground for a company whose idealistic founders, Page and Sergey Brin, once railed against the perils of allowing money to influence which Web links to show.
Brin and Page preached about the issue in academic papers that they wrote about search while conceiving Google as Stanford University graduate students. They also delved into the topic when they outlined Google's "don't be evil" creed in a letter written to potential investors before the company went public in 2004.
"Our search results are the best we know how to produce," Brin and Page wrote in the letter. "They are unbiased and objective, and we do not accept payment for them."
Microsoft contends that Google is doing a disservice to its users with the new approach, as many users may not even realize that the results in shopping search are being swayed by money.
"We want consumers to know, in contrast to the route that Google has pursued, we are staying true to the DNA of what a good search engine is really about," said Mike Nichols, Bing's chief marketing officer. "We will rank results on what's relevant to you and not based on how much someone might pay us."
Danny Sullivan, an Internet search expert who has been following Google since its inception, believes Microsoft is highlighting an important issue. "Google deserves to take its lumps on this," said Sullivan, who now works as editor of SearchEngineLand.com. "I have been surprised by how little attention this issue has gotten so far because it's a 180-degree turn for Google."
Sullivan doesn't think Bing's shopping results are pristine, either. He points to Bing's partnership with Shopping.com, which also requires merchants to pay to be in its listings. Some of Shopping.com's data is fed into Bing's shopping section. When Shopping.com gets paid by a merchant for sale funneled through Bing, Microsoft gets a slice of the revenue.
While all that is true, Bing's shopping section consists mostly of listings from merchants that haven't paid for the privilege, said Stefan Weitz, Bing's director.
That's so, Weitz said, even though Bing isn't currently accepting listings from new merchants that want to appear in its shopping results. The only way a new seller can get into Bing's shopping search engine is to sign up for Shopping.com's fee-based service. After the holiday season, Bing's shopping-only section once again will accept free listings from new merchants, Weitz said.
Like Google, Sullivan said Microsoft isn't doing a good job disclosing the role that money plays in its shopping-only results. He thinks that issue could undermine the effectiveness of Bing's anti-Google ads.
Microsoft's attack site: http://scroogled.com
Google shopping site: http://www.google.com/shopping