The use of what we call "profane" language being offensive has always been a mystery to me. We assign words meaning, which means we take some arbitrary sound and seed it with a definitive purpose so the word in and of itself isn't in any way bad. We decided to make some words bad or off limits which is a little irrational. When I was young and swearing was a no no in my house hold I routinely used replacement words like "oh shoot", "what the heck", or "freak". None of those words were deemed bad by my parents and other adult authority figures with the exception of perhaps one crazy sunday school teacher. However, the intent behind those words and their "more adult" counterparts was the same. When I needed to exclaim disgust and spilling a gallon of milk the only difference between oh shoot and oh shit was that we as a society deem that word to be bad or in poor taste. The fact that I could say oh poop and not get my mouth washed out while oh shit just wasted good hand soap was completely idiotic, as poop and shit are only really differentiated by taboo. Too much use of any word whether it be a swear word or not is the sign of smaller vocabulary, but as Carlin noted some of these words have multiple meanings which makes them more useful than some words which are much more limited in use.
Now that's not to say that I don't understand trying to keep kids vocabularies "clean" because words can be just as dangerous as a chainsaw or other power tools I wouldn't have a young kid using. The words of dictators, religious fundamentalists, and other general "bad guys" have stoked and created terrible conflicts within the world. However, with kids using swear words it's the same as with a power tool, I don't let them use it because they're not yet capable of understanding the full repercussions of the use of such things. The words we choose to use should be chosen with care and thought, with audience and the true intent of our communication in mind. When kids learn to use these bad words correctly (usually by practicing their use away from encroaching parental and authority figures) all the sudden it becomes clear that with a little guidance they too eventually learn to use the full beauty of the english language in a manner suiting their contemporaneous and present situation. They learn that in a classroom, fuck is not a very good thing to say, but when their with their mates outside of the classroom it's perfectly acceptable to use that word to convey just how bad that dead leg they just received felt.
I always just tell kids that there are grown up words that should be used judicially and if they don't understand what the words mean or how to use them they should refrain from using them just like I tell kids the chainsaw is a tool that you should not us until you have the strength and have been shown how to properly use them. Just like I don't teach small children words like orgasm, and clitoris as they're not really useful to children but after they grow old enough they should know what both of these are. If we never told kids that these words were bad or unclean in the first place they'd never know and instead of creating some arbitrary value system for words being good or bad we could actually just help children with their vocabulary when they use these "bad words". We correct kids when they use the wrong verb conjugations like telling them it's "I saw a bear not I seen a bear", so I don't know why we assign such vitriol towards some words. It's one of those societal taboos that is only backed up by our own collective hallucinations like most of our value systems and we should question this taboo. After all the words genocide, rape, and molestation all mean some pretty rotten things, but the words themselves aren't bad and are in fact very useful to describe this world around us which can be pretty rotten at times.