I've been watching Farscape again and I love the way they handle profanity.
If you haven't seen it they have a neat little mcguffin to handle the fact that all the alien species speak different languages but understand each other with perfect clarity. All the characters are infected with "translator microbes" that enable them to understand any language spoken to them. They are also quite consistent with it in that uninfected characters can't understand each other.
As for us, well we understand everyone except for when the plot works better if we don't understand.
The interesting thing is that swearwords are NEVER translated so we hear a constant stream of "dren", "boll-yotz", "farbot", "fekkik", "hazmot", "tralk" and "frel".*
The only other things that don't translate tend to be units of measurement. Obviously they can't include the swearwords or they would never get on air but the context makes the meanings of the substitutions clear.
Moral little beasties those translator microbes.
(*in English, that's shit, bullshit, crazy, ass, bitch, whore and f**k)