This post is purely personal opinion.  I’ve been doing a bit of thinking about why I don’t typically like songs with swearing in. I don’t think I’m a huge snob… I’m not terribly bothered when people use the occasional swear in normal speech. Well, I might be a bit shocked if it was the vicar doing it, I suppose, or my mother. But normally if I hear something when I’m out and about, I’d just think of the swear words as being part of the person’s everyday vocabulary and mentally translate, without considering the words’ literal meaning.

 
I get the argument that art needs to reflect life, and in real life lots of people swear. Most, maybe, in the UK, where I live. It’s not like I never use any swears myself for emphasis either, when I want to make a point and underline how something makes me feel. I’m not ruling out ever using strong words for making a point in my music, even. I just don’t like there to be swears in the music I listen to, as a general rule… it seems unnecessary, usually.
Part of the issue is that listening to music creates a kind of personal space. Swears in music can feel like a violation of that boundary. Another reason is that I pick up language and absorb it like anything. If I surround myself with foul language, it’s bound to seep into my mental vocabulary, even if I don’t verbalise it. I’d prefer for the strongest language to not get in that far, even, and with music I have an abundance of choice about what I can listen to. Why choose something with swears in?
Music, to me, is a beautiful form of art, as well as being a means of expression. I feel that some swear words are particularly ugly, especially the f-bomb. Given the choice, I prefer to listen to something that reflects my idea of beauty… I don’t automatically reach for the off button the instant there is a swear, but will do if there are lots of them in a short space of time.  If a song is littered with swearing, if it is intended for the swearing to help get a message across, in my view, the song loses impact.
Some songs seem to get away with having the odd swear in. I can’t think of a good example off the top of my head, but, like film violence, if it’s not gratuitous, if it makes sense in the context of the story that is being told, or is done in a humorous way, I can stomach it. I was thinking Fairy Tale of New York might be a good example, but when I checked the lyrics, I found the Pogues hovering over the fine line of using strong insults and coarser language without actually swearing. You might disagree and conclude that they cross the line with some words. It’s a close call.
On the other hand, I object somewhat to cleaned-up versions of songs for the radio, if a version that is available to buy is not going to have the expletives deleted, e.g. if it’s going to be the version on the album. I heard and liked the Ce-Lo Green song Forget You on the radio, but was disappointed when I heard that it was a clean version of the song and discovered what the ‘real words’ were. Some people got caught out buying the ‘non-clean’ version on the basis of radio-play, as well, and were even more disappointed than I was, as I understand it from the grapevine.  I’m not sure what Ce-Lo Green did with his album, but I would feel cheated if I bought an album based on liking a cleaned-up single and then the version on the album was a different version of the song I liked, with expletive non-deleted lyrics. It would mean they were a different artist to who I thought they were. It would almost be a betrayal.
Apparently there is already technology available that would allow you to bleep out offending words, when it works.  Apple also have a patent on software with a similar aim. No problems of course with instrumental music…