Same with everything else in life, we tend to be more offended by something that is 'foreign' or different to our experience. Personally I don't find foul language too offensive, but then I worked in 'Civil' construction for over a decade, so I guess I got used to it, and I naturally have a 'whacky' sense of humour.
However, there is something that does annoy me, and that is the slide back into regional accents and pronounciation across the English speaking world. I am old enough to recall when most people presenting on Radio and Television back in the good old days used Received English, at least in England and Australia. Sadly Received English is in decline and even well educated people on TV etc now present information in their local dialect.
Call me old fashioned but it's really annoying when some young Scientist from Northern England delivers lectures using terms such as Pacific for Specific and Somethink for Something. I mean the Northern accent is bad enough without the poor grammar