Most, as in probably slightly more than half of BM characters I run into are routinely vulgar, and I think I have approved all but one 'is this vulgar' request I have ever received, the one exception being a fairly obvious case of what Velax was talking about where it was just revenge. I rarely submit messages as vulgar unless they are really bad, though, because frankly I'd be doing it all day otherwise.
Whether or not the OOC motivation of the person judging the message is revenge, tons of people expose themselves to this all the time, and it is one of the few actual mechanisms of smacking people in the head with a reminder that they are supposed to be medieval nobles and not dudes in a pub playing pool.
The recent Dakra/Caglia post-battle exchange was an absolutely typical example. A high class, e.g. noble medieval insult is not easy for us, and that's not a bad thing - remember how we got rid of the aristocracy in most countries? Even among rich people, actual 'upper class' (as in status/behavior) rather than just 'has money' is pretty rare all over the world. It's why 'Downton Abbey' is so popular: it's something we hardly ever run into!
Finally, remember the currency you're using when you're marked as 'vulgar.' It doesn't injure you. It takes away honor and prestige. Maybe a lot of people think of these things as 'points,' but they're not points, they're honor and prestige. This by no means requires you to play an honorable, prestigious character - in fact one whole character class is dedicated to doing pretty much the reverse.
But if you're going to concern yourself with vulgarity and its effects on your character, then you should avoid lowbrow humor. And plays, by the way - theatre was considered quite vulgar until the late 1500s and even then it was generally still vulgar to actually participate in it as a writer or actor.
