medical language is to a vast extent a binary. i've taken a cultural anthropology class where we discussed the language of western medicine (i know there are problems with the designation "western", but i don't have a more accurate word for this as of yet), and things are generally yes or no. either you are disabled or you are not; either you are healthy or you are not; either you are ill or you are not.
of course, all is shades of gray.
in psychology/psychiatry one generally uses the term "unhealthy" to imply that a person is doing/thinking/believing something or in some way that is significantly inhibiting their ability to function the way they would like to. i think that holds some degree of water here as well. though that does bring up the interesting point of impact on others: is it possible to be a healthy antisocial person? is it possible to be healthy and still want to do harm to others? perhaps a better idea of health is relative: how are you doing compared to how you could be doing, not compared to anyone else.
anyway, as for the forum, someone pissed off at another type (or another person of the same type) could totally call unhealthy when they just don't understand the other person or want to accept their reasons (of course an ENFP can't be hateful! or, well, they must be unhealthy!)
healthy =/= likeable, though i imagine a healthy person would have a better chance of it .