I think swear words are extremely valid and valuable in today's society. I am a teacher of English to adults in Switzerland and last week I had my first "swear word" class. It was a very cool class and I had a personal thrill getting the whole class to repeat "motherfucker" after me. Lots of words that are standard to me they had never heard of. We discovered all the different ways "fuck" could be used, adjective, verb, phrasal verb and a number of nouns. It's pretty useful. We also played "the fuck", putting those words between shut and up or sit and down to make them a bit forceful. For learners of English dictionaries can actually be quite useful and if they don't want to completely loose out to the internet, maybe they should keep up with the language.