The online review appeared to be a glowing endorsement of a fine hotel by the shores of Loch Ness. “My parents stayed many years ago and said what a lovely spot this place has. They were so right!” said the review of the Drumnadrochit hotel posted on TripAdvisor, one of the most popular websites for travel information.

“Well done to the staff, who were really charming... Have no hesitation in booking... the food is outstanding... Believe me you’ll love it.”

The gushing praise, however, was not the independent judgment of an ordinary guest: in fact, it had been written and posted by David Bremner, the hotel’s owner.

Last week he admitted the ploy but was unrepentant. “Maybe I shouldn’t have done it,” he said. “But I don’t think it’s that big a deal.”

Real guests might not agree: some previous reviews had complained of high prices and shabby rooms.

Either way, Bremner is certainly not alone in exploiting the booming number of online travel guides that allow the public to post their own reviews of hotels and restaurants.

When the Old Bore at Rishworth, a 200-year-old country pub in West Yorkshire, reopened earlier this year one reviewer was moved to rave about the food.

“Stunning new pub restaurant,” gushed the writer on eGullet, a website for food connoisseurs. “Roux brothers scholar opens Old Bore at Rishworth, just been awarded dining pub of the year by Robert Cockroft. Tried it!”

Scott Hessel, who posted the eulogy, failed to mention one significant fact: he happens to be the owner of the Old Bore. Hessel, who trained as a chef under the Roux brothers and Marco Pierre White, last week admitted that he should have revealed that he was the proprietor, but denied that he had been attempting to mislead readers. “I was misinterpreted,” he said.

Last week another popular website, allinlondon.co.uk, featured a review of The English Maid, a 70-year-old Dutch barge that has been moored on the Albert Embankment in London and was recently converted into a restaurant.

“New Menu is amazing value (2 course & coffee £10),” enthused Mike Halliwell, the reviewer. “Can you get a fillet steak or calf's liver anywhere else for £5!!? Best value in London.”

Yup, Halliwell happens to be the owner of the English Maid — but did not mention it in his review. Last week he claimed this was a “mistake” and insisted that he had in fact been trying to contact the editor of the website rather than post a message.

These examples are just the tip of an iceberg. The entire industry of reviewing hotels and restaurants is in the midst of a revolution that risks leading customers up the path to Fawlty Towers.

The traditional published guides, often compiled by independent inspectors, are struggling, while online sites where checks are few are proliferating.

A Sunday Times investigation has shown:

1) “Guests” who have never even stayed at a hotel can boost or depress its rating by posting fake reviews.

2) Poorly rated establishments can lift their reputations from one to four stars in a matter of hours by posting fictional positive reviews.

3) Some establishments attempt to damage the reputations of rivals. So tough is the competition that even top hotels and restaurants would consider placing fake reviews to maintain their status.

The best travel guides have traditionally been compiled by professional inspectors who visit hotels and restaurants incognito and fiercely guard their impartiality. But it is a costly business and one that can no longer compete.

The current issue of the RAC hotel guide, which employed 12 full-time inspectors, will be the last. It has emerged that the company which publishes Les Routiers’ UK guide, which had eight inspectors, will go into liquidation this week; it said that competition from websites had helped to drive it out of business.

Adam Raphael, co-editor of The Good Hotel Guide, draws a stark contrast between published guides and online review sites. His guide relies on reports from inspectors and an established database of 13,000 readers.

“We know their tastes, the quality of their judgments and where they are coming from,” he said.

“Online sites are like a lucky dip. You may be lucky and you may find someone of reasonable judgment. On the other hand, you may have someone who is in the pocket of some hotel or restaurant. It really is a swamp.”

Nor are famous names necessarily a safeguard online. Fodor’s, the travel guide publisher, boasts that it has “spent over 65 years building a reputation for objectivity and high standards”, but its website is rather different to its printed guides.

Among London hotels on Fodors.com, for example, is the Vandon House in Victoria, which received a rating of just 1.2 out of a possible five after a scathing review last year. A guest from Ohio had complained of stuffy rooms, “unbelievable” noise from other guests, an unwanted 1am wake-up call, and “miserable” beds.

Yet last week reporters posing as fictional guests managed to boost its rating to 4.2 — ranking it among the capital’s top establishments such as Claridge’s — simply by posting four reviews giving the hotel top scores in all categories.

Fodors.com immediately published the reviews and failed to check whether the writers had stayed at Vandon House. Tim Jarrell, the New York-based publisher of Fodor’s, later said: “The website is a buyer-beware service. You do not know who’s necessarily reviewing those sites or properties.

“It could be someone with an axe to grind, a competitor, it could be the chef, it could be almost anybody.”

However, he added that in the light of the Sunday Times investigation the site will in future read all reviews before publication.

Other leading online guides include TripAdvisor.com and IgoUgo.com. Last week The Sunday Times was able to post reviews on TripAdvisor giving top ratings to six London hotels that had consistently been criticised as “the worst ever”, “a horror” or “disgusting”.

One hotel in west London had received consistently bad reviews on TripAdvisor, with guests describing it as a “hovel” with “stains everywhere”. Yet when a Sunday Times reviewer awarded it top marks, no one checked on the discrepancy.

TripAdvisor, which insists that all its reviews are read by moderators, later admitted that it could not spot all fake postings but aimed to stop concerted campaigns to raise the reputations of establishments.

The chaotic nature of online reviews is tempting some hotels and restaurants to fight back by whatever means are available. An undercover reporter claiming to represent a marketing company approached a number of hotels and restaurants offering to post favourable opinions about them on travel review websites.

When he asked Bridget Pearse, manager of Vandon House, whether she would be interested in signing up to the service, she said: “You can definitely see the logic in it. It will depend on costings and things . . .” She later told The Sunday Times that manipulation of reviews by hotels “in principle does not seem right”.

Senior staff at some of Britain’s top hotels and restaurants also seemed keen. Stuart McPherson, general manager of the Cowley Manor hotel near Cheltenham, which is on the Condé Nast Traveller “Gold List” of the world’s top 108 hotels, said: “I’ll probably need some more information . . . I think in principle it sounds quite nice, because I think we’ve all been stung by various things on . . . TripAdvisor or the likes, and you like to have some sort of recourse.”

The hotel later said McPherson was under instruction to receive all marketing offers politely, but that any material would “have been thrown in the bin”.

Real marketing firms are already advising clients that they should persuade guests to promote their hotels and restaurants using online reviews. Jason Price of the New York-based agency Hospitality eBusiness Strategies, agreed that hoteliers could use their own staff to post glowing reviews.

Price, who said his firm’s clients included leading British hotels, also told an undercover reporter: “(You can) create some internal incentives to encourage a guest to stay at the hotel, and then go on and post a review.”

Price’s boss later said this does not occur.

Earlier this month Sir Tim Berners-Lee, the British inventor of the worldwide web, warned that his creation risked being overwhelmed by tidal waves of misleading and false information. “There is a great danger that it becomes a place where untruths start to spread more than truths,” he said.

Many travel sites would argue that it has not come to that yet. The benefits of forthright reviews from real customers, they say, outweigh the pitfalls.

Nevertheless, there is no denying the sea change under way. By using reviews supplied free of charge, online guides can avoid the costs of inspectors, hotel and restaurant bills, and printing costs. At the same time they can funnel visitors to online booking agents and take a commission for doing so.

The commercial pressures mean that even leading publishers of traditional guides such as the AA and Alastair Sawday are being forced to consider setting up websites carrying consumers’ own reviews, despite doubts about their reliability.

“We’re doing it nervously,” said Sawday. “There’s a lot to be said for reader reviews — they make a site richer and more democratic. But it may turn out to be disastrous. If it doesn’t work, we’ll pull out.”

It is not just the publishers of guides that can suffer in the new free-for-all. The former proprietors of one hotel in Torquay are, according to one website, suspected of sending threatening letters to three guests. Why? Because they dared to post negative reviews about the hotel on TripAdvisor.com.

Basil Fawlty would be proud.

Additional reporting: Megan Kaesshaefer

GUIDE TO THE GUIDES

THE TRUSTWORTHY

Michelin Guide

Michelin employs 500 anonymous inspectors across Europe. The 121 Michelin-starred restaurants in the UK are visited several times each year. No reader reviews.

AA Hotel and Restaurant Guides

A team of 30 full-time inspectors anonymously reviews 4,000 hotels and 1,800 restaurants across the UK. No reader reviews.

Good Hotel Guide

Printed guide that rates hotels according to user reviews, but also carries out a small number of its own inspections. It says it monitors veracity of guests’ opinions.

Alastair Sawday’s Guides

A total of 300 hotels are anonymously inspected each year. Places included in the guide pay between £50 and £900 to appear.

READER BEWARE

Toptable.co.uk

Online restaurant booking site that had 1.6m visitors last year. It checks with restaurants to ensure reviewers have eaten there.

Activehotels.com

Aims to weed out misleading reviews by allowing only people who have booked a hotel through the site to write reviews.

City-eating.com

Has 1.5m visitors a year. Anyone can post a review, but a full-time moderator flags up dubious ones.

TripAdvisor.com

The biggest travel review site with more than 20m visitors a month. People must register before posting reviews, but anyone is allowed to register. Moderators attempt to catch irregularities.

Fodors.com

Currently makes no checks before reviews are posted but says it will do so in future.

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