Google announced on Wednesday that it had changed the way it ranks search results so that unscrupulous merchants would find it harder to appear prominently in searches.
The change was prompted by an article in The New York Times on Sunday about Vitaly Borker, a Brooklyn-based online seller of eyeglasses. Mr. Borker claimed that he purposely shouted at and frightened some of the customers at DecorMyEyes.com because the online complaints actually worked in his favor in Google search results.
In essence, he claimed, Google's search engine is unable to tell the difference between positive posts and withering online critiques. Therefore, the more complaints posted about Mr. Borker's site, the more likely customers would be to find his store ranked high on a Google search, which yielded him more revenue.
In a blog posting titled "Being bad to your customers is bad for your business," Google said that it had revised its algorithm so that it could detect Mr. Borker and "hundreds of other merchants that, in our opinion, provide extremely poor user experience."
Google did not reveal how it had changed its algorithm, or how that change would affect online sellers like Mr. Borker. It simply said that the more it reveals about the changes it made, the easier it will be for unscrupulous sellers to game it.
"We can't say for sure that no one will ever find a loophole in our ranking algorithms in the future," Amit Singhal, a Google fellow, wrote on the blog post.
"We know that people will keep trying."
With the changes, Mr. Borker has already had a harder time pushing DecorMyEyes to its previous high rankings on Google. The store once showed up on the first page of a search of "Christian Audigier" and "eyeglasses." As of Wednesday night, it was not in the first 20 pages.
Mr. Singhal said that the change was made after the company read in The Times about the ordeal of Clarabelle Rodriguez, who bought a pair of glasses and contact lenses from DecorMyEyes in July.
When she tried to return the frames and get a refund, Mr. Borker (using one of his favorite pseudonyms, Tony Russo) commenced a campaign of phone and e-mail harassment.
That included threats of litigation and chilling statements like "You put your hand in fire. Now it's time to get burned."
He also sent a photograph of the front of her apartment building, and in a separate e-mail wrote "I AM WATCHING YOU."
Ms. Rodriguez went to the police several times and on Oct. 27, Mr. Borker was arrested and charged with aggravated harassment and stalking.
He is set to be arraigned on Dec. 22.
The Internet is rife with consumer complaints about DecorMyEyes, and even the quickest search of the store's name yields dozens of outraged testimonials.
In July, Ms. Rodriguez's search used only the brand name of the glasses she wanted. DecorMyEyes was at the top of Google's main search page.
"We were horrified to read about Ms. Rodriguez's dreadful experience," Mr. Singhal wrote in the blog post. "Even though our initial analysis pointed to this being an edge case and not a widespread problem in our search results, we immediately convened a team that looked carefully at the issue."
Exactly how Mr. Borker wound up so high in Google searches has been a matter of online debate. His theory is that the great mass of grievances on all those highly regarded consumer complaint sites were the key to his success.
Google cast doubt on that idea, saying that consumer complaint sites typically include special coding along with the mentions to the companies in question so that such links do not count in the companies' favor in search results.
At the blog Search Engine Land, Byrne Hobart also wrote in a recent posting that the review-generating strategy was not the driver of Mr. Borker's success. His analysis found that Mr. Borker benefited chiefly from various "black-hat tricks" to improve his site's standing, including links from what he called auto-generated spam pages. He also found that the store was frequently linked to by mainstream media sites -- The Times included -- when references were made to high-end eyeglasses.