While it's never ideal to use bad words, I make it very clear that there are certain times and places where they're more acceptable than others. If you're in a private place with friends who are comfortable with cursing, there are no young children around, and no one who will think less of you/will dislike your word choice can hear you, it's acceptable to curse. However, while there are times that you can "acceptably" curse a blue streak, you may want to save those words for a time when you need them.
I know that sounds odd - like, when do you "need" to use bad words, let alone any type of word? I think everyone speaks in certain ways to certain people. (After all, would you feel comfortable saying "what up?" to your principal?) You "need" to use certain words with certain people. When you use language you don't usually use, people are more likely to listen to you. For example, if you normally liberally sprinkle like in your conversation (a crime I am guilty of) and make an effort to cut out the likes in a particular conversation, people will probably listen to you and take you more seriously. If you often curse, people will get desensitized to that type of language and will be less shocked when you use bad words. However, if you make an effort to keep your mouth clean, people will be extremely shocked that you cursed.
This can work both ways. People will be shocked in a bad way: if you, someone who always speaks with precision, cursed, how much more will they think less of you! (In the Old Testament, Miriam was severely punished for speaking petty gossip about Moses. One explanation for this was because she was on such a high spiritual level, she was punished more harshly than someone else would have been.) It can also work in the opposite way: people will also see that you really mean what you are saying. Once I was talking with one of my friends, and she said, "Please excuse my language, but she is such a b***h!" While there may be better words out there to use than the b word, by using such strong language that was totally uncharacteristic of my friend, I understood how annoyed she was.
Don't you want to have those bad words stored up if you really need them?