In medicine, pain is an often-overlooked vital sign, and it's very difficult to know the level of pain people are in (if any) based on their report - and that's the only way we have of doing it. That may be changing. An fMRI study of 114 people at U of Colorado showed >90% sensitivity and specificity for objective pain detection. Each subject was their own control, since they were subjected to painful and non-painful heat. The team was even capable of fairly reliably discriminating between social and physical pain.
"...there is good and bad speculation, and this is not an unparalleled activity in science...Those scientists who have no taste for this sort of speculative enterprise will just have to stay in the trenches and do without it, while the rest of us risk embarrassing mistakes and have a lot of fun." - Dan Dennett