See I would argue that swearing isn't a problem in itself. It's context that matters.
All words have meaning and are expressive. Using swear words appropriately isn't an issue. They shouldn't have a status where they are forbidden in all contexts either because that gives them a power which can be used in a negative way.
We don't have a problem with swearing in front of DS. We figure he's going to hear it often enough at school. We take the attitude we'd rather teach him how to use swear words well and in a way that isn't going to get himself into a whole world of trouble.
Therefore teaching him there is a time and place for swear words and that they shouldn't be used in certain places or to certain people is more valuable than a complete ban on them.
Swear words are amazing words in their own right. We under value them or misuse them. That's the issue.
Parents who don't swear at all save up a bunch of their own issues because it means you close a level of communication off. It means you actively say some conversations are verboten and off limits.
DS is not allowed to swear. Not unless he has been 'given permission to' or it's not in our earshot. He understands we know kids swear and it's part of the language of growing up. He knows we swear and it's an adult thing. The point is we are teaching this and how swear words have boundaries and are almost ring fenced into certain situations. And they should not be directed at people in an abusive way.
We've said it's better for him to understand the meaning of swearing words rather than just use them without knowing what they mean (the literal meaning and the contextual slang casual meaning). This he is permitted to come and ask us about any word or phrase he does not know or knows has a 'bad' meaning.
All communication is communication. We want to encourage in a positive way and to ensure language is used creatively, contextually and accurately. It has a time and place.
Ranting away on MN is often a fucking good release of anger and frustration over emotive topics. Swearing can help to convey that or to slightly deintellectualise when it might be getting very serious or word salady. It's a sledgehammer word too.
The thread about the teacher yesterday couldn't make my eyes roll hard enough. It sounded like the teacher either had had a bellyful from the class or was communicating in a way to indicate to the kid that he should fuck off before he pushed his luck further in an informal manner. It wasn't abusive. Teachers who swore at school tended to be those who got the kids best and had the respect of the kids ime. They knew when it was appropriate and when it was absolutely not and when it would get them into a pile of trouble... Of course there is no accounting for jobsworth parents who go 'swear word = bad and wrong' rather than a more pragmatic 'is the teacher being abusive or are they communicating in a different but effective way?'
It is possible to be too uptight about swearing. It's is possible to be too free and thoughtless about swearing.
I think there's an intelligent middle ground.