Buying positive product reviews is unethical and sometimes illegal, but always sleazy. Yet the practice flourishes on popular sites like Yelp, TripAdvisor, Google Places and Amazon, according to research firm Gartner.

Online reviews, especially those posted at marketplaces like Amazon, are more popular purchasing tools than is word of mouth, according to a survey by Econsultancy. And bloggers remain a popular target for trading positive critiques for cash, coupons and promotions.

But just as attractive are social networks, which are where more than half of the Internet gathers. With so many potential customers in one place, companies are desperate to build follower groups and gather more praise than competitors.

The Rise In Bogus Reviews

Having watched the online reputations of some brands rise quickly, many execs are ready to pay for even dishonest praise to catch up. A study by Cornell University found that from 2% to 6% of reviews on Expedia, Hotels.com, Orbitz, Priceline, TripAdvisor and Yelp were bogus, and that total is rising.

Companies are paying for Facebook "likes" and Google+ "+1s," along with hits on YouTube videos. The practice is found among media, entertainment, consumer goods, retail and consumer electronics vendors, Gartner says.

By 2014, Gartner believes 10% to 15% of all social-media reviews and ratings will be “bought” and at least two Fortune 500 companies will face litigation from federal regulators for trying to deceive consumers.

Who Sells Buzz?

Roughly 50 companies sell buzz on social networks. One example is Social Jump, which charges $75 for 1,000 Facebook likes. For an extra $10, clients get geo-targeted likes, Gartner said in a recent report, "The Consequences of Fake Fans, 'Likes' and Reviews on Social Networks." The Facebook thumbs-ups comes from real people, not spam bots. Social Jump also sells "+1s" on Google+, followers on Twitter and thousands of views on YouTube videos.

Other companies operating in the same market include MyFBfans, SocialKik.com and Fan Bullet. Along with these companies are a number of reputation-management organizations paying people to write good reviews for clients.

When Fake Reviews Are Illegal

Paying a blogger or anyone else to write a glowing review is not illegal, as long as it is disclosed to the reader. Of course, doing so would gut the article's effectiveness, so a lot of times that detail is missing. In 2009, The Federal Trade Commission published guidelines for such disclosures on blogs and other new media and has been ramping up enforcement ever since.

For the first 18 months, the FTC handed what amounted to a slap to companies who had too cozy a relationship to bloggers. By mid-2011, the FTC meant business, fining Legacy Learning Systems $250,000 for hiring marketers to get good reviews on sites for one of the company's educational DVD series.

Building Consumer Confidence

More hefty fines and media exposure of companies paying for positive ratings and reviews is key to building consumer confidence, said Jenny Sussin, a Gartner analyst and co-author of the report. "We actually think that's going to increase consumer trust."

In August, Facebook announced that it would start cracking down on likes that didn't come from real fans.

In an indication that the purge has begun, PageData reported last month a big drop in likes for popular pages, including Zynga's Texas HoldEm Poker and FarmVille, as well as those of pop singers Rihanna, Lady GaGa and Justin Bieber.

Separating The Good From The Bad

Despite efforts to stem illicit reviews, consumers will have to be on guard to spot fakes.

Sussin recommended reading multiple reviews and watching for details, such as comments about a hotel’s good service but small rooms. Credible reviews typically point out good and bad features.

Reviews that are over the top in criticism or praise should be suspect. "If something is too inflammatory, you can't trust it," Sussin said. While companies plant good reviews of their own products, they also hire people to badmouth competitors.

Paid reviews ultimately bring only short-term benefits. The company may get some new customers initially, but a poor product can't withstand the test of time. Such short-sightedness is not new in business, and has driven misleading marketing in the offline world for a long time, keeping regulators busy. The Web won't make their jobs any easier.