There are a few people who can use a well placed swear word to punctuate a conversation and sound more savvy than the rest.
Quite right. It's the mindless use I find tiresome.
It's rather like vibrato in singing. Done occasionally, with artistry, it can enhance the music. Done continuously, it can obscure the music.
Sometimes, though, vulgarity is more a matter of laziness in language (and in thinking?). In LineagAG's example of the hypothetical professor who says "Your thesis is a bunch of shit.", only the prof's disapproval is communicated. If he had bothered to make actual criticisms, something useful would have been communicated, and the prof would not have lowered his own dignity.
Does one encounter the phrase "infra dig." anymore? It used to be quite common but I've not seen it recently. It's short for "infra dignitas" and refers to something that would lower one's dignity, or entitlement to respect, if one did it.
What actions might be infra dig is a matter of social custom, or manners. I was once asked why one should bother with manners. My reply was that they make it possible to stand having other people around. I haven't seen any studies, but my impression is that societies with careful manners are also those with high population densities (eg Japan). I wonder if there is indeed a good correlation there.
[aside] I once mentioned this idea (preserving one's dignity) to one of the boys in our Scout troop. He was surprised anyone thought he was entitled to any, since he was still young. [/aside]
I merely prefer elegant writing, that's all. If someone else doesn't, it isn't that important.