Children tend to use words to express themselves, often these words are not always what we deem appropriate but I am of the theory you must pick your battles with children. Setting clear rules that are stringent enough to produce a strong well mannered child is important, but giving flexibility also allows the child to grow independent and with high self esteem.
The fact is both you and her father are raising her, but when you disagree about something and the child knows this it is confusing to the child and can give her incorrect views on who is in authority and who has the final say so in the family unit. It is best for the child to learn and see that both parental figures work together to achieve a goal instead of being at odds.
I personally think that the words are not appropriate at certain times, but neither do I think they should be banned completely either. I would recommend sitting down with your husband and explaining to him that by disagreeing on the subject you both are teaching the child that one parent has more authority then the other. What your children did or did not do has very little bearing on the subject..........no children are alike and your daughters were raised under set rules thus there was no one saying it was OK to do something you said no to. Thus this was not a issue.
Ask your husband if there can be some rules on the matter and some common ground. Such as when you are with company (Friends, family, church, etc) she is not not use these words. But when she is alone, or at home it is OK. This gives the child the Independence to use them should she want to, but sets a example that while there is a time and place for it the fact is it is not appropriate everywhere. Same rules as when she was a child............running and screaming at church would not be appropriate but at home at play it is OK. The key is to show her that in certain situations she must control her actions.
I understand that you do not wish to hear them all the time, but the reality is she is a teenager and picking your battles is a better route then trying to control completely. Dad has a point, this is something he has no issue with so getting a change in the rules is unlikely. Even if you can get dad to lay down the law, she is likely going to blame you since dad was OK with it before. Consistency is the key, changing the rules up is never a good idea when dealing with a teenager, even more so when it is a blended family. She has a game plan with the rules already, if you join the game and start changing the rules on her it is going to become a battle of wills. And children often become the winners when a step parent is involved. Creating drama and tension in the family unit. Sometimes it is better to take a step back and allow the little things to pass..........that way when a large issue arises (Which typically does with teenagers) you can voice your concern then and your husband and step daughter will be more apt to listen.