Umm... Personally I prefer good manners above almost anything. The odd quip should just add to the fun... without offending.
However, I guess there are also those who believe that debate has to be hot in order to reach a resolution and bring out all ideas / beliefs / and otherthingummies.
If we ignore these people we are prejudging them and ignoring what they have to say based on our assumpotions about who they are.
(I know - this is all "liberal hogwash" but I'm gonna say it anyway).
If you do reply to these people and they just continue grunting away being rude then you know to leave it, but they might just try and join in the debate and have something fresh to say.
Hyp