I just read Hallucinations by Oliver Sacks, and he describes an experiment where volunteeers told doctors they were hearing voices, and with no other symptoms they were diagnosed schizophrenic and hospitalized, even though hearing voices is actually really common and schizophrenia is rare. I'm generally a fan of psychiatry because I'd be in big trouble without my meds, but there are way too many doctors out there just half-assing it.