A mystery check or also called mystery guesting is a method to evaluate the service quality, standards and various procedures of a hotel business from the perspective of an expert or hotel guest. An anonymous hotel tester is used who visits the establishment without prior notice and evaluates it according to predefined criteria. With the help of a mystery check, results can be recorded under real conditions without the respective establishment being specifically prepared for the test. In Austria, mystery guesting as part of hotel classification can only be carried out by companies that are listed in the official pool of the trade association and use the predefined questionnaire.