Trivago is extending its Hotel Test scheme to the UK and Ireland after its initial launch in Germany last year.
The mystery guest programme has a number of elements. Users sign up as a hotel tester and receive incentives of up to £70 from Trivago for completed online surveys of about 400 criteria on hotels they stay in.
The results and reviews are displayed on the Expedia-owned metasearch site to build profiles of the hotels and integrated into Trivago's filters to improve the search process.
The hotel test results can also be purchased by hoteliers costing from £2,000 for which they get results from between 20 and 100 testers who have paid full price for a stay over a two to six month period.
Hotels are promoted on the site during the test period with Trivago saying this "guarantees" between 20 and 100 bookings.
The properties also receive weekly updates of test results as well as a market comparison at the end of the testing period with the guest insight, which can be based on location, region or number of stars, to benchmark against competitors.
In the UK and Ireland, the mystery guest programme goes across 40 hotels in 10 cities including London, Dublin, Edinburgh, Liverpool, Birmingham, Manchester and Glasgow.
The programme is already available across 12 European cities including Rome, Madrid and Berlin.
Trivago says the scheme creates "accurate and genuine hotel profiles" and that more than 20,000 hotel tests have been carried out for 600 properties.
The company adds that 20% of testers are regular testers of hotels in different cities. In addition, 100 German hoteliers have purchased the hotel reports including some big brands.
Online travel companies have been moving to ensure the authenticity of reviews through initiatives such as TripAdvisor's Review Express service, unveiled almost a year ago.
Trivago has also launched a beta for a Social booking service to the site enabling groups of people collaboratively research and vote on the best hotel for a stay.