Whether invective is intelligent or not depends on context. I've found Shakespeare's insults to be quite entertaining and witty, and many modern strings of curse words can be too, if well done.
OTOH, if you're using the same words over and over again, well, you're just robbing your words of their power. I still think the edited version of "My Name is (Slim Shady)" is linguistically superior to the unexpurgated one- Eminem had to really work to tell his story without vulgarities, and his wit shows. It contains some talent that he only rarely flashes.
In college, I used to curse like an Australian sailor in constant pain. Then I gave up cursing for Lent- not hurling invectives, just certain words that had crept into my vocabulary so much they seemed like conjunctions- so I had to come up with other things to say. I must say, it was quite satisfying to call someone a "Rooster Licker" and walk off, leaving him standing there puzzled; he realized what I said just about the time I was getting in my car- a verbal "hand grenade."
These days, I curse much less than I used to in college, and when I give up cursing during Lent, I give it up completely. I try not to curse in front of kids under 14.
To me, its about a lot of things- respect for others, being a better person overall, etc.