In our acute care center we could always spot them by their claiming to have maladies that cannot be diagnosed definitively. In other words, one cannot send them for a diagnostic test that would either confirm or deny their complaints as substantial.
These are also the ones that we watch for being drug seekers....chronic, but undiagnosed, pain is the primary complaint and they have used it for many doctors in the area...one only has to call any local pharmacy to see how many times they have received pain med scripts and from how many doctors.
It jades a person in health care so much to be dealing with these types of patients. Especially when you also deal with people with real illness~ who would give anything to be well.