I can't stand those "potty words" that's what we call them. Try some soap in the mouth. I know it sounds awful but it worked on my oldest - he stopped. And remember what works with one kid may not work with the other - where is she hearing these potty words - make sure that you watch your own language as well.

If time outs aren't working, a dash of something she doesn't like on her tongue may do the trick. For example, vinegar or mild hot sauce. A little bit goes a long way! Always follow up with a talk about why the words are inappropriate. I believe strongly in setting expectations and consequences with children rather than just punishing. Good luck!