Scientific data on this topic is conflicting. However, recent clinical trials suggest that people who are sensitive, such as men who are prone to acne, can develop acne when eating a normal quantity of chocolate (1,2)

1. Vongraviopap S, Asawanonda P. “Dark chocolate exacerbates acne”. Int J Dermatol. 2016 May;55(5):587-91.
2. Caperton, Caroline et al. “Double-Blind, Placebo-Controlled Study Assessing the Effect of Chocolate Consumption in Subjects with a History of Acne Vulgaris.” The Journal of Clinical and Aesthetic Dermatology 7.5 (2014): 19–23. Print.