The easiest way for a psychologist or psychiatrist to identify a psychopath or sociopath or any other of the myriad mental health labels is to gaze into a mirror.
One can entertain distinctly low opinions of the bulk of psychiatrists, psychologists, therapists and social workers without dispensing with the idea that some diseased people among us are bent on killing (-path, -pathy) or destroying things, such as properly functioning human minds (psycho-) and/or the basic tenets of beneficial human life in community (socio-).