So when TripAdvisor, the world's most used travel review site, heard a ruling last week from the Advertising Standards Authority that its reviews could be misleading and 'non-genuine', it should have recognised a looming crisis. Last year thousands of hoteliers challenged TripAdvisor's strapline, which claimed users 'find real hotel reviews you can trust'.
For the past decade TripAdvisor has revolutionised tourism. It handed power back to consumers, who for too long had been treated with contempt by many hotels and restaurants.
It was particularly powerful in this country, because Britons had always been averse to 'making a scene' when they suffered poor service.
Moreover, TripAdvisor was a prime example of a new 'social' medium. Why would one need old media's professional travel journalists when one could hear from millions of 'real travellers'?
For many of us TripAdvisor became the first thing we checked when booking a hotel or restaurant, not least because it nearly always appeared on the first page of a Google search.
Unfortunately, as it became bigger and more powerful, the site has become a victim of its own success. Once hoteliers realised the awesome power of this site, and some reviewers recognised their individual power, the purity of the project was diluted.
Unethical hoteliers were tempted to post positive reviews anonymously, often - as they saw it - 'to make up for unfair, malicious reviews'. Some went further and launched anonymous attacks on their rivals.
Some reviewers, drunk on their new-found power, wrote myriad, pernicious reviews of establishments.
An excellent Channel 4 documentary last October, Attack of the TripAdvisors, showed the heart-breaking damage that amateur reviewers had wrought on hard-working hotel-owners.
Many of us also found the reviews were becoming less useful to read, often polarising between 'the hotel from hell' and 'my dream holiday', and averaging out at an unhelpful four stars.
TripAdvisor's response to the ASA ruling has been along the lines of '50 million users can't be wrong'. But it should not underestimate this dwindling trust. The model requires a serious overhaul if it is to continue an impressive growth curve.
As we have seen in recent debates over Wikipedia, social media are empowering and enlightening, but they can still learn some lessons from old media in terms of rigour and trust.