Background: Nowadays, aesthetic dermatology treatment has become not only physical beautification but also it can have positive effects on patients’ mental health. Body dysmorphic disorder can be the reason for treatment dissatisfaction. In the general population, the prevalence of BDD is 1.9% and it is more common among cosmetic patients. The aim of this study was to conduct the most comprehensive evaluation of body image and BDD among aesthetic patients. Methods: We recruited a group of 412 individuals, who were asked to complete 6 different on-line questionnaires concerning self-image, i.e., COPS, AAI, FAS, BAS-2, BSQ-16, and RSES. Results: The prevalence of BDD ranged from 7.28% to 11.17%, depending on the screening tool that was used. Our research revealed that BDD susceptibility, body image, body appreciation, and self-esteem were strongly interrelated (p < 0.001). A higher BMI was a risk factor for BDD, body dissatisfaction, and depreciation. The financial status markedly influenced all of the features. A history of psychiatric treatment influenced the risk of BDD, body satisfaction, body appreciation, and self-esteem. A history of cosmetic procedures and treatment satisfaction had no impact on the obtained results. Conclusions: Improving recognition of body dissatisfaction among aesthetic patients is very important. The psychometric assessment of patients before cosmetic treatment could be of help in choosing the appropriate approach.