E., your daughter is feeling her way into a new stage of personal growth so, in some respects, she is testing her limits with you. Five year olds don't fully understand the foul language they may pick up but, like all other words they learn, they try them out. How your daughter relates to the new words (ANY new words) depends largely on how you do. If you react with alarm and totally freak over a chosen word, she will quickly learn she can get your attention whenever she feels the need simply by peppering the air with a few well chosen profanities! This will, in fact, set the stage for later potential combats and, if you send the wrong message now, you will have already lost the battles that will come later! Stay cool and calm and always remember your job is not that of punisher but instructor.
I have always thought such harsh reactions as "washing your mouth out with soap", vinegar spray, even 'popping them on the mouth' were mean-spirited and fail to address the real issue. Each of these methods seems to be sending the wrong message and teaching the wrong lessons. Even something as seemingly benign as vinegar spray is pretty harsh when you consider five year-olds are still, for the most part, very innocent and will, for the next ten or twelve years, be learning and absoring all of the important life lessons they will need as adults. They don't have all the answers yet. That is your job to help them find the answers. It seems pretty hard core to be punishing a child little more than a toddler for something they haven't learned yet. That's sort of like taking a third grader who is learning to multiply and divide and giving him a test on advanced calculus, then making him stay after school because he doesn't know what a cosine is!
Raising children is not so much about punishing undesirable behavior as it is about TEACHING and ENCOURAGING appropriate behavior. In the case of your daughter's "testy" language, try sitting down with her in a non-confrontational environment (maybe sitting on the floor in her bedroom together) and, first, ask her where she learned the words. Then ask her if she knows what they mean. If she does not, your preamble would be to ask her why she uses the words if she does not know their meaning, then explain to her what they mean.
If she does know their meanings (and have her explain them to you) proceed directly to the next step: Ask her why she would use such words. Tell her that these words are used by people who do not have sufficient vocabulary to find more appropriate words to express their feelings. Tell her that using such language suggests that she is not smart enough to use better words and makes other people think so, too. This, btw, applies to boys as well as girls, men as well as women. (I must confess I have been guilty of it myself but there is really no excuse, other than shock value, for anyone to use foul language.)
Talk to your daughter about how important it is to choose both your language and your friends carefully and talk to her about how the wrong choices can effect her whole life. Speak to her in language she can understand and exact from her a promise that she will try to choose her words more carefully in the future and to choose better words. (You also want to make sure she understand the importance of making a promise and how a promise is all about being an honorable person within herself). Then, when you hear her using inappropriate language, just remind her of her promise and talk to her again about why she chose to use the inappropriate word and perhaps help her find a better word choice. (When my kids were small, we used to make up words that more adequately expressed the internal feelings of the moment. It was fun to create silly words and an anger filled situation soon would disintegrate into giggles whenever they used their silly anger words.) Imagine, if you will, and angry youngster stomping his foot and shouting "Oh, shnicklefoop" especially in front of strangers! My grandson has traded in more scathing language such as "motherf***er" and "Gd Damn it" for less offensive counterparts of "mother father" and "God bless me". And it has the unexpected bonus side effect of diffusing a little bit of the anger as well.
One last note: be sure to keep your discussion on a level your daughter can understand but don't make her feel as though you are talking down to her. It's okay to improve her vocab in more subtle ways as you talk, like every now and then use a word she may not know and explain it to her so she will be able to use it properly. And be sure to watch your own language and remind your spouse to monitor his word choices as well. Make it a habit to spend some personal time with your daughter on a regular basis. I always found just before bedtime to be a wonderful time. Sitting together in the middle of her bedroom floor, or helping her pick up and put away her toys, is a great opportunity to talk about her day and any worries or problems that may be on her mind. It also helps to quiet her down to make the transition from day and play to sleep. And, if you encourage open conversation now, you may be able to avoid violent verbal encounters later - both because you are both in the habit of comfortable, trusting, open conversation, and (and this is the big part) because you will have learned how to deal more calmly with disagreements which will, in turn, help you to stay in control of the conversations. Even if she decides to escalate a disagreement, you will be able to DE-escalate because you have already learned how to stay calm and retain control.
Good luck and lots of love.