The times that I've gotten snippy or nasty, I usually regret later. I don't like to be a nasty person, doesn't matter if I'm right or not, its just lacks class. Being able to walk away and not respond, to not let others push our emotional buttons I think is a good thing.
I also think that for a while, newbies should just be given the benefit of the doubt. Let them defend the JW beliefs, let them be newbies. Kicking somone whos already down has no honor. Are JW beliefs so tough that we need to get nasty to logically defeat them? I think a mild gentle honest answer speaks more than a 'zinger', and it doesn't activate their defenses.
But I also do enjoy witty, cheeky sarcsm. I think the balance needs to be found between polite public behavoir, but not sappy fake nice either. We all need to grow thicker skins, and become less reactive. I also don't like PC, as I think it is the worst of fake, and ushers in censorship in the guise of tolerance.
So my point blank answer: No, it doesn not have to be nasty, and may actually be more effective when not.
Same goes for face to face meetings, louder dosent' mean right. I hate loud people, ok their speech not them.