[nomadking]

In general, if you are calling somebody a X...(usually descriptive in some way) Y... for a reason, as long as there is a reason for the Y..., then because the X... is classed as an ism, shouldn't make a difference.

If you get into an argument with somebody, then all sorts of things will be said. As long as the Y... is deserved in the context, then any X... shouldn't allow the other person to get away with bad behaviour of whatever sort deserving the Y... part.
If somebody who is X attacks you, and you call them a X... Y..., why should the X... matter?