Interesting post. As you've commented, context is nearly always the thing that enables us to behave or act in ways we're most comfortable with.
The societal conventions of who you swear in front of are constructs guided by the notion that some members of society, usually female, aren't equipped to handle the abrasive nature of so-called 'bad' language. The fact that some of us refer to it as 'bad' language never fails to puzzle me. I'm a good case in example. I came from an inner London working class family, and my parents attempted to clamp down on any use of swearing by myself. I can understand why, imagine your child going to school and swearing liberally in front of teachers. The havoc this would cause is self-evident, so a childhood is generally a time when you are taught to act and speak in a certain way, mainly without the use of swear words.........but then childhood turns to the teen years and the beginning of adulthood, and once this begins the shackles are well and truly removed where language is concerned. I swear regularly, probably as much as anyone I know, but the use of the word 'respect' has never been something I've had a problem with. I'm 'respectful' to most people, and nearly always without the need to swear, but that's because I don't know them, and familiarity is the key to when, and how much, I swear. When I'm confronted by fully formed adults who complain that I swear to much, and tell me how much they loathe swearing, my response is usually uncomplicated, I tell them not to swear if they find it offensive. I don't like smoking, I don't drink alcohol or the effects this has on those who drink regularly, but I never dream of telling them how to behave.
The example of the Americanism 'motherfucker', and how you perceive it's influence on language and behaviour, is interesting. It's another swear word, one that is now a part of the vocabulary of those who are relaxed about swearing. As for how influential swearing is, how it erodes our general behaviour, how it contributes to our perceptions about other people's worth, is something I've given thought to. I can't say I'm convinced by this argument. I think there are many other factors about the world we live in that contribute to how we react with each other. Television and cinema have an influence on behaviour, although I don't think this influence is sufficiently strong enough to worry me. The world changes, and with it so do we. I did note that although you used almost every swear word going, there was an absence of the word 'cunt', a word that trips off of my tongue with ease. I think the point I'm coming to is that we create our own 'limit's' or 'boundaries' in which we feel comfortable, and when those 'limits' are confronted by the behaviour of others, we respond either aggressively or abruptly, mostly as ways of warning the offending party that behaviour or words that invade these 'boundaries' we've created aren't welcomed.
During my life I've had a variety of jobs, journalism being one such. I've written for high profile newspapers and magazines, both in the UK and America, so you might assume that my interest in, and observance of, language would be central to how I manage to articulate an idea or thought. I think I'm a classic example of being (partially) defined by my upbringing. I don't happen to see swearing as 'wrong', or something that's embraced by those who have a restricted vocabulary, whatever that might mean. Swearing is as much a part of an evolving vocabulary as that changing society that I referred to earlier. Whether you like it or agree with it should only be reflected in your personal life. Attempting to tell others how they should behave will generally be met with a response that isn't favourably disposed to your suggestion. Of course, if that behaviour includes such ideas as racism, homophobia, or acute sexism, then challenging it is down to the individual, especially if they feel they can have a positive influence on those who choose to use language that is harmful to other social groups. What I can't advise on is how brave or foolish you might need to be in such a situation, but from personal experience I've sometimes felt the need to offer a position that is opposite to those who consider it ok to use racist language as if it's the norm. It might be their norm but it's certainly not mine.....but this takes me away from the gist of this post. Swearing shouldn't be consigned to some box marked 'offensive'. It can be used as constructively or descriptively as any other means to capture an idea. If I meet someone for the first time you won't hear me swear, simply because I choose not to assume about the other person's thoughts on swearing. But once we're familiar in a social context, and it's obvious that swearing isn't a problem, well then I'll use whatever language I feel is appropriate. Trust me, I know what I'm fucking talking about.