Body dysmorphic disorder (BDD) is a serious illness in which a person is preoccupied with minor or imaginary physical flaws, usually of the skin, hair, and nose.A person with BDD tends to have cosmetic surgery, and as a rule, is unhappy with its outcome.ody dysmorphic disorder (BDD) is a serious illness in which a person is preoccupied with minor or imaginary physical flaws, usually of the skin, hair, and nose.