The increasing obesity rates in the last decades pose a challenge to health care providers, and bariatric surgery is an important tool for treating severe obesity. Because various psychological factors are known to influence the long-term outcome of bariatric surgery and failure of bariatric surgery can lead to psychological harm, candidates for bariatric surgery usually undergo thorough psychological evaluations before being approved for surgery. However, the information obtained through these evaluations comes primarily from self-report measures, which are largely influenced by the ability and willingness of individuals to focus on and describe their own psychological characteristics. To examine the extent to which different assessment methods yield different psychological profiles of bariatric surgery-seeking patients, 50 patients with obesity (BMI = 44.9 ± 6.4 kg/m2) seeking bariatric surgery and 29 eutrophic controls (n = 29; BMI = 23.1 ± 2.8 kg/m2) were administered: (a) some self-report measures assessing psychopathology and emotion regulation; (b) a maximal performance (neuropsychological) test; and (c) a typical performance (personality) test. Statistical analyses showed that when compared to the control group, patients with obesity self-reported lower levels of mental illness, although they showed poorer performance on the maximal performance test and increased defensiveness on the typical performance test. We conclude that the use of a multimethod approach and the assessment of positive response bias are crucial in pre-surgery evaluations.