Answer: Watch out for the repeated therapist-shopper who declares you’re the one who can help him!

From Daniel Kahneman’s book Thinking:Fast and Slow:

As a graduate student, I attended some courses on the art and science of psychotherapy. During one of these lectures, our teacher imparted a morsel of clinical wisdom. This is what he told us: “You will form time to time meet a patient who shares a disturbing tale of multiple mistakes in his previous treatment, He has been seen by several clinicians, and all failed him. The patient can lucidly describe how his therapists misunderstood him, but he has quickly perceived that you are different. You share the same feeling, are convinced that you understand him, and will be able to help.” At this point my teacher raised his voice as he said, “Do not even think of taking on this patient! Throw him out of the office! He id most likely a psychopath and you will not be able to help him.”

Many years later I learned that the teacher had warned us against psychopathic charm, and the leading authority in the study of psychopathy confirmed that the teacher’s advice was sound. The analogy to the Muller-Lyer illusion is close. What we were being taught was not how to feel about that patient. Our teacher took it for granted  that the sympathy we would feel for the patient would not be under our control; it would arise from System 1. Furthermore, we were not being taught to be generally suspicious of our feelings about patients. We were told that a strong attraction to a patient with a repeated history of failed treatment is a danger sign–like the fins on the parallel lines [of the Muller-Lyer illusion]. it is an illusion–a cognitive illusion–and I (system 2) was taught how to recognize it and advised not to believe it or act on it. (p 27-28)