On Saturday night, like many other young women in Shanghai, 25-year-old Angela Xie was going to eat out with her girlfriends. Xie works in the banking industry in Lujiazui and usually checks out possible restaurants on dianping.com, a review website where almost every restaurant, salon and shop in Shanghai is listed alongside comments and ratings from customers on prices, service, food and ambience.

On this day she fancied Cantonese cuisine and searched for "Cantonese food" in the People's Park area. Dozens of restaurants showed up. "It's almost a ritual for me to look up dianping.com to see which restaurants are popular. Usually I am interested in the restaurants with four or five star ratings and these are the places I'd think about trying," she said.

Xie is like millions of young people around the world who are now guided by online reviews - a phenomenon unknown before the Internet and mobile phones became commonplace. The concept of democratic reviews written by ordinary people has been a selling point for many.

But these websites, with their user-friendly honest reactions to goods and services, have been infiltrated by fraudsters who post fake reviews in return for payments from the companies involved. The US technology research firm Garnter has estimated that by 2014 between 10 and 15 percent of all online reviews will be fake.

Businessweek reported that Liu Bing, a University of Illinois at Chicago computer science professor who's been researching into fake reviews, estimated that for some products, more than 30 percent of online reviews are fake.

Special investigation

A Global Times investigation has revealed that many underground companies have appeared in recent years, promising to promote the reputations and ratings of businesses in cyberspace.

Search for "Dianping" and "review" on the shopping site taobao.com, and dozens of companies are listed, claiming to offer professional marketing strategies on dianping.com. But what they actually do is charge clients between 30 yuan ($4.82) and 50 yuan for writing a fake review, depending on the business.

Posing as the owner of a newly-opened cafe eager to promote her shop, the Global Times contacted several of these companies. A 25-year-old Beijing man called Hu Can, who apparently works for one of these companies, offered this advise on the phone: "For a start-up business, I suggest you upgrade your ratings to four or five stars first, and then gradually increase the number of reviews so that your cafe will appear in the first page of the search results."

Hu charges about 1,000 yuan to lift a restaurant to a four-star rating. "About 15 to 20 positive reviews will do this. To avoid suspicion, we'll post the reviews over one to two weeks." He said that if there was a sudden overnight increase of reviews for one business, dianping.com could detect this and would delete them.

"So I recommend a long-term investment. Many restaurants work with us for up to a year to slowly and steadily increase the number of positive comments. Three of the top 10 restaurants in Shanghai on dianping.com are working with us right now, although we cannot reveal their names," he claimed.

Hu forwarded his company's "Client Brief" which includes a series of questions eliciting details of the businesses involved. The brief asks: "What products and effects do you want us to stress in the reviews? e.g. promising to lose 5 kilograms in a month, or the fact that you use fresh New Zealand strawberries in the desserts? Which star staff member do you want us to mention in the reviews? Hairstylist Coco, photographer Wang Min or your foreign chefs? How do you want us to mention your ambience? Cozy or luxurious?" Clients can also choose the length (between 80 and 200 words) and ratings for each review.

Hu said: "We aim to create a story in each review to impress the customers. When we have these details we're able to make the stories more creditable."

According to Hu's transaction record on Taobao, thousands have already bought his services.

Increased traffic

Another taobao firm promises to increase the website traffic for businesses as well as writing fake reviews.

The way Dianping works means that traffic and ratings decide how near the top of the search results businesses can appear. To keep a business showing it has at least 500 visitors from different IP addresses a day looking at its webpage, the firm charges 1,200 yuan a month. "All are local IPs so there is little to arouse suspicion," the contact said.

On zhubajie.com, a website that promotes itself as a crowd sourcing firm, companies can post requirements and users can bid for small jobs and tasks. Many businesses come here directly, hiring people who own Dianping accounts to write reviews for them. Here, a review costs 4 or 5 yuan.

Some firms contact small restaurant owners directly to promote their business. Dai Yan is a 40-year-old woman who runs a sushi outlet in Jiading district. She said that she and other franchise shop owners were regularly contacted by public relations companies offering to boost their online reviews. "Some say they can delete negative reviews, and some promise to improve our ratings."

But Dai has never considered using the firms. "We trust our food and we don't need to buy fake reviews. I think it's risky anyway. Most of our customers are young people who are smart and technologically savvy. If we bought fake reviews and they discovered them, it would destroy our credibility."

She did admit, however, that two family members had written positive reviews for her restaurant. "In recent years I've noticed the ratings on dianping.com have become inflated. Now it isn't uncommon for a restaurant to have four or five stars. But as far as I can remember, this wasn't the case in the past. As an insider in the food industry, I use dianping.com more as a tool to tell me the location of a restaurant."

Dianping.com has been battling fake reviews for more than three years and has zero tolerance with them, said the company's public relations manager, Yan Liting. Up until 2010, the company had manually deleted fake reviews. After 2010, it upgraded its system and started to use algorithms to detect and filter fake reviews daily.

"The technical department upgrades the algorithms almost every day. Also, if users find a shop with large numbers of suspicious reviews, they can report this to us and we'll investigate and delete the reviews," Yan said.

Established reviewers

Another change in dianping.com in 2010 meant that only reviews by established reviewers appeared on the main pages of businesses. Established reviewers are unlikely to provide fake opinions.

Yan said that in 2011, the company punished 77 companies which had been found to have bought large numbers of fake reviews. The punishments included having all reviews deleted, along with ratings and traffic counts and being prohibited from accessing dianping.com for 90 days.

But some established reviewers on dianping.com have also been in the sights of fake review companies. Registered in December 2007, the dianping.com account "Immigration to Burma" has posted 2,966 reviews since then and is now eighth on the "most reviews" list of Dianping members. In real life "Immigration to Burma" is Tang Lei who works at a securities company and said that he only posted reviews because he loved food.

"Many business owners and public relations companies have contacted me, offering money or other inducements for posting good reviews for them. But I'm not interested. First, the money they offer is meager, and I don't do this for a living. Second, I write reviews out of interest. It's not right to write fake reviews," he said.

Tang said some companies were buying large numbers of minor accounts and "cultivating" them until they appeared to be established accounts. He offered advise for consumers who wanted to know how to distinguish between fake and real reviews.

If a review offers nothing but praise, it might not be for real. "No matter how good a business is, there are usually some shortcomings and reviewers should mention these. If there are no problems talked about, it's suspicious."

Tang said consumers should also check out other reviews by the same reviewer. "Some reviewers might be found offering comments on different wedding photography outlets within a few months which would be improbable. How many weddings can a person have in one year? Sometimes you can discover that at one time the reviewer is a woman having a facial in a spa and then later she became a man dining in a restaurant with his wife. Inconsistencies like this show this account is probably owned by a marketing company."

If the reviewer has never written a review before and only registered just before the comment was published, the review should be treated with suspicion. And he warned that timelines were an important factor in telling real from fake. "If the favorable posts on a page appear within a short period of time, be very cautious."

It was revealed last month that the industry and commerce administration authorities in Changning district last year fined a media company which had posted fake reviews for other businesses. The Shanghai Paris Wedding Photography Studio, which bought reviews from the company, was also fined.

Cheng Shi'an is a professor of advertising at Fudan University and said fake reviews emerged several years ago on shopping and review websites and were rampant in 2011. "For the past two years, as more and more customers recognize the tricks, they have become relatively less brazen. It's a fraudulent and unethical way to promote a company, and it's very risky. I would never suggest companies do this because if consumers find out, they would never want to visit your shop again.

"Also, writing fake reviews breaks the laws for fair competition. Although in reality it is hard to collect proof, companies should realize they're breaching the law this way," she added.