During my psychiatry rotation in med school, on some mornings, we would have patients come into our sitdown rounds and attendings would interview them. This was actually very interesting (and also awesome because I got to sit down).
One of the patients I will never forget was a college age kid named Riley who was presented as having his first schizophrenic break. He had been admitted a few days earlier and the med student sitting next to me (Jason) had taken him as a patient.
Riley was a skinny kid of about 20 years old with dyed black hair who had recently dropped out of college. He didn't seem particularly happy to be there, but he didn't seem particularly schizophrenic either. But what did I know?
At one point, the attending said to Riley, "When did you start hearing voices?"
Riley frowned and said, "I don't hear voices."
At the end of the interview, the attending sent Riley back to his room and stated that he would "bet anything" that the kid was hearing voices. The attending highlighted the fact that Riley couldn't tell us what his parents did for a living as particularly odd and strong proof of his schizophrenia.
At that point, Jason (the med student who was following Riley as a patient) nudged me and pointed to something he had written on his notepad in big capital letters: "GAY"
Jason's theory, he later told me, was that Riley wasn't schizophrenic at all and was actually just struggling with sexuality conflicts.
I can't say I ever found out the truth about Riley. But I did later read about a study where some "normal" people were admitted to a psychiatric ward and subsequently just acted like themselves.... and the psychiatrists would explain all their "normal" behavior in terms of psychiatric disorders. Like when the subjects were taking notes on their experience, the psychiatrics observed "compulsive notetaking."