Around one in 10 product and service reviews on social media sites will be paid for by businesses by 2014, according to analyst company Gartner.

There are two ways in which business pay for reviews on social media sites, Gartner analyst Jenny Sussin explains. One involves either company employees or marketing agency staff pretending to be consumers posting positive reviews.

"There is actually a whole market out comprised of vendors who exclusively promise you more Facebook likes or YouTube views,” Sussin says.

The other approach is to pay home workers to post positive reviews on a pay-per-post basis. "There is a whole other market for actual written fake reviews – usually another quick buck to be made from home," Sussin explains.

"The main victims are review-specific sites like Yelp and TripAdvisor," she says. "Many marketers have turned to paying for positive reviews with cash, coupons and promotions including additional hits on YouTube videos in order to pique site visitors’ interests in the hope of increasing sales, customer loyalty and customer advocacy through social media ‘word of mouth’ campaigns."

The use of these services will grow, Gartner expects, despite attempts by regulators to crack down on false adveritising. Nevetheless, companies must be aware of the risks they face in using paid reviews.

"Marketing, customer service and IT social media managers looking to use reviews, fans and ‘likes’ to improve their brand’s reputation on social media must beware of the potential negative consequences on corporate reputation and profitability,” said Ed Thompson, vice president and distinguished analyst at Gartner.

“CMOs will need to weigh the longer-term risks of being caught and the associated fines and damage to reputation and balance them against the short-term potential rewards of increased business and the prevailing common business practice in their market, often regardless of ethics.”

In the UK, the Consumer Protection from Unfair Trading Regulations, which is enforced by the OFT, states that paid reviews would constitute an “unfair commercial practice” unless they are clearly marked as such.

“When it’s an online review that’s been paid for, we would consider it to be like an advertorial, like when you’re reading a newspaper or magazine and you see a boxed out sponsored feature with a note," an OFT spokeswoman told Information Age. "If that’s the case online, whether it’s a tweet or a review, then the financial relationship needs to be made clear."

The OFT said that if a company breached these guidelines, we would seek undertakings, which are a legal commitment for that business in which to operate, and to make the promotion clear that it’s been paid for. Should they breach those undertakings we could potentially seek a court order."

They added that specific complaints against particular advertisers would be investigated by the Advertising Standards Agency or, in the case of local firms, by Trading Standards.