I can't see any moral justification in attempting to stigmatise those we perceive to be wrong by means of name-calling, only personal satisfaction at expressing our imagined superiority. Calmly stated and well reasoned polite argument or counter-argument without insult or accusation, on the other hand, might just stand a chance of actually changing someone's opinion. Perhaps.

Name-calling belongs in the playground, not in reasonable debate or discussion if it is to be productive. We all know bigots exist, and that some people are bigoted about some things, but there is really no need to point at them and shout 'bigot' - that's no better than calling the fat kid 'fatty'. Real bigotry is self-advertising.