Yelp reviews: Can you trust them? Some firms game the system

To fight back against fake testimonials, Yelp has developed sophisticated algorithms to root them out. And it employs a team of staffers whose job it is to detect fraudsters. At left, Yelp CEO Jeremy Stoppelman, with fist in air, celebrates with employees during the company's IPO at the New York Stock Exchange. (Justin Lane, European Pressphoto Agency / July 4, 2012) 

Yelp works to keep suspect reviews off the website. Recently, members of a Southern California business networking group were ordered to stop giving five-star ratings to one another.

By Jessica Guynn and Andrea Chang, Los Angeles Times
July 4, 2012, 5:05 a.m.

SAN FRANCISCO — Judging from recent reviews on Yelp, the Center for Counseling, Recovery & Growth was the place to go to turn your life around.

The Torrance center racked up 14 coveted five-star ratings on the popular review site for its "warm and friendly therapists" and "beautiful offices." Many of the testimonials made similar points, sometimes in nearly identical language.

That was no coincidence. Acting on a tip, Yelp uncovered what it dubbed a "review-swapping ring" composed of members of a South Bay business networking group. Yelp said it was a coordinated effort by members to boost their ratings by posting glowing reviews about one another's businesses.

(More here.)