Article about a fake doctor caught in Texas. Essentially, people trust doctors who seem to be good listeners: The Make-Believe Doctors: "In an unkind cut, the report stated that the people of Groveton should have known that Reid Brown was not a doctor because he did too many things wrong. For example, he made house calls for five dollars and charged only three dollars for an office visit. He approved of Medicare and would drive for miles to visit a patient, often without fee if the patient was poor. Besides, his handwriting was legible.
What were the secrets of Freddie Brant's success as an impersonator? They were many, but the main ones were his readiness to refer any potentially complicated case to nearby towns, a personality which inspired confidence, and a willingness to take time to listen to his patients."