Researchers from the Peninsula College of Medicine and Dentistry, which carried out the research, found that specific groups of doctors fared worse in patient and colleague feedback surveys.
Worse patient feedback scores were associated with factors including doctors being trained outside Europe.
Colleague feedback was worse for doctors including those trained outside the UK and south Asia; doctors working as a locum, as a GP or psychiatrist; and for those with few colleagues reporting frequent contact with them.
The researchers warned 'caution is necessary when considering patient and colleague feedback regarding doctors' professionalism'.
Study lead Professor John Campbell said until the results of all doctors' patient and colleague surveys are analysed a comprehensive view of their potential benefits and concerns cannot be obtained.
He said colleague surveys were an important element of revalidation. 'What we have is a developing story which will lead to a more robust questionnaire process in time,' he said.
'The main message from our findings is one of caution - that the public, the regulator and the medical profession must be careful about how the results of such questionnaires are used.'
GMC chief executive Niall Dickson agreed that the research shows the results of patient and colleague surveys should be 'treated with care'.
He said: 'Being aware of how patients and colleagues view your practice is important for every doctor but it is only one part of the supporting information that doctors will bring to their appraisals.
'It will be considered alongside all the other information about a doctor's practice and is not something which you can "pass" or "fail".
'It assesses an individual doctor's strengths and areas for development to help them improve their practice - it is not a way of comparing doctors with one another.'