For some reason (probably because I've NEVER heard my parents swear), swearing is really unnatural for me. For a brief period in college I tried it out, but then decided it's really not for me. So I don't swear. Neither does DH, unless he's been playing a lot of Grand Theft Auto, then some slip out.
Never around the kids, though.
Anyway, I wouldn't love it if my kids picked up swear words, and I would tell them that I prefer they communicate in a different way. We're sort-of struggling with this right now, as DD (five years old) has picked up "Oh my God!" from somewhere. Her bus driver, it seems? We are atheists and I don't personally have a problem with that, but I know that some of the people DD interacts with will, so I've been trying to get her to stop, telling her that some people take God really seriously, and hearing her use this expression might hurt their feelings. I haven't heard it in a week or so, so maybe it's sinking in.
We have a CD right now that my FIL made for the kids, and one of the songs on there is Johnny Cash's "Boy Named Sue." At the end of the song the line is "I'm the ----beeeeeeeeep!---- who named you Sue." My kids are incredibly intrigued by that long beep, and asked me what he was saying. I explained the concept of swears, saying there are some words that a lot of people consider impolite and that singers aren't allowed to say on the radio, and so sometimes these words are replaced by a beep.
Then, of course, the kids wanted me to tell them the words. I politely declined. Sorry, kids, I'm not teaching you all the swears today. You're on your own for that part of your education.
If they come home saying swears or asking about them, though, I'll certainly talk about them calmly. I just don't think I need to give a 5-year-old and a 3.5-year-old those words right now.