I teach my child not to swear because OTHER adults think there's something wrong with it. I truly don't give a fuck, but I don't want my son to be banned from his best friend's house because his mom heard him say "fuck."
My 12 year old's school allows swearing, and while it is curiously disturbing to hear a six year old swearing like a sailor while playing a video game, it is interesting to see what happens to the older kids as the novelty wears off. I allow my child to swear, but he respects which words I would rather not hear around the house, and I've never heard him swear when it was inappropriate. So, I teach my son how not to be banned.
As someone who's considered this tactic (I'm some years away from having children, but planning seems like a good idea), I'm interested in how that's working out. Have you ruined cursing for your kid as some people imply this tactic would?
Well, he's 4 and, although he knows every bad word except "cunt," he knows better than to say them, at least in front of grown-ups. But cursing is not ruined for him - he still thinks cursing is hilarious and he frequently asks me to say a bad word.
I would say it's working out. He doesn't offend the tribal elders and I don't have to lie by simulating outrage - I've told him the real reason why he can't curse.