From time to time there are random angry or confused users posting an offensive post, with a username containing bad words like f***, penis or nigg**. There also occasionally new users submitting their first, legitimate question or answer, with a username containing the same set of keywords. Those users usually don't get nuked, but always get their username reset by a moderator, to "user123456".
So the conclusion is rather clear: There's NO legitimate reason for a user to have a name containing such offensive keywords, and it's only more disturbance and disruption.
Would it be useful to ban (or automatically delete/suspend users with, or censor them after a grace period) such usernames? We could at least block these words that commonly appear:
f\W*u(\W*c)?\W*k nig+[aeu][rh]?s?, penis, pus+ys*
P.S. It's quite an interesting fact that we're blocking "Problem" in titles but not "f**k" anywhere.