Video report by ITV News Consumer Editor Chris Choi
Travel website TripAdvisor is failing to stop fake reviews boosting the rankings of top-rated hotels, Which? has claimed.
The watchdog analysed almost 250,000 reviews for the top 10 ranked hotels in 10 popular tourist destinations around the world, finding one in seven had "blatant hallmarks" of fake reviews.
Which? Travel reported 15 cases to TripAdvisor and claimed the site admitted 14 of them had already been caught with fake positive reviews in the last year.
It said TripAdvisor revealed that six of these hotels had been penalised for breaking guidelines and two had previously been given a "red badge" warning for suspicious activity, but this was not made clear to travellers.
Which? said TripAdvisor had taken down hundreds of reviews following its investigation.
Adam French, a Consumer Rights Expert at Which? said they have found an "alarming amount of fake reviews on TripAdvisor that could be misleading people into wasting their time and hard earned money on holidays that do not live up to expectation".
He added: "We urgently need TripAdvisor to take serious action to get these fake reviews off their website".
However James Kay, the director of Corporate Communications at TripAdvisor, said "in most cases we're able to stop fake reviews from going onto the site".
So how can you spot a fake review?
Check for repetition - the same phrases appearing constantly are a bit of a giveaway
Look at the time those reviews are posted - if a lot of five star reviews appear within minutes of each other be suspicious
Shop around - check lots of other websites - if all the claims are similar they are likely to be genuine
What did the Which? investigation find?
One hotel in the Middle East, rated as the "best hotel" in Jordan, had a "hugely suspicious" pattern of reviews, Which? reported, adding that the unnamed hotel denied any wrongdoing but TripAdvisor subsequently removed 730 of its five-star ratings.
At the "best hotel in Cairo", according to TripAdvisor’s traveller rankings, some 79% of five-star reviews were left by profiles that had made no other contributions on the site.
Shortly after Which? shared its findings, TripAdvisor removed reviews from the property and it lost its status as Cairo’s best hotel, the watchdog said.
In Las Vegas, two of the 10 highest-ranked hotels received almost half (48% and 41%) of their hundreds of five-star ratings from first-time reviewers who had never made any other TripAdvisor contributions before or since, raising suspicions that they could be fake, Which? said.
In contrast, another hotel near the top of the Las Vegas rankings had just 3% of its almost 2,000 five-star reviews from once-only reviewers.
Which? Travel also compared 10 London hotels at the two biggest UK chains, Premier Inn and Travelodge.
While Premier Inn did not arouse suspicion, almost half of the hundreds of five-star reviews at two Travelodges came from first-time contributors who had never reviewed anywhere else.
The findings come as the Competition and Markets Authority (CMA) is carrying out a programme of work aimed at tackling the increasing problem of fake and misleading reviews.
A TripAdvisor spokesman said: "It is simply far too simplistic to assume all first-time reviewers are suspicious.
"We have a dedicated team of fraud investigators who work tirelessly to protect the site from fake reviews."
A Travelodge spokeswoman said: "We did experience a breakdown in our internal communication when TripAdvisor identified an irregular pattern of reviews at one of our hotels – Wembley Central Travelodge.
"Unfortunately on this rare occasion that matter was not managed effectively within the timeframe, and we have taken appropriate action to ensure this does not happen again."