Unfortunately, this labeling and clinging onto the early hypothesis happens all too often in daily life. For medical diagnosis, we wish the standards would be higher, but at the very end, there is a human making a judgement.
When analyzing, I often realize that I give more weight to who said something, rather than what was said.
Sad but true?
I may have the story wrong, but I believe that a relative--involved in the court system, not medicine--took part in one such experiment, and reported that the patients had no difficulty in distinguishing the pseudo-patients.