From my experience: There is often a bit of real roughness and lack of kindness when people talk in a cynical or sarcastic manner. Even if it's not insulting anyone, watch closely the circumstances under which people say something like "What the f*** is going on?". Do people say something like this when something nice happens or if there is a hint of something being "not-so-nice" ? Either way, talking in a rough way can stirr up the mind more than non-rough talk, which would be something to look out for when one aims for higher levels of concentration in and outside of meditation.
Whether it's unwholesome khamma always depends on the situation, too. LP Wän Sucinno once uttered this verse that is a rare example for a monk speaking more roughly (rough translation):
Past is daffy,
Future is daffy,
Present is Dhamma.
Past is drunkenness
and future pure unreasonableness
only present makes awakened.
Remember that untill you are sure.
Stop with the chattering, because
too much talking is not Dhamma.
It is daffy.
Obviously LP Wän Sucinno had quite a blunt way of talking about things, perhaps because people in his environment were more reciptive to this style and/or it was a matter of personality. In this case though, it is a means to transport wisdom (!) and it does not address anybody as a person (!), so that's a rare intention for using a tougher language. I'd always be careful with calling people names, it is a big difference between saying "You are dumb" and "What you just did was dumb." - even if it is not meant serious, people make more of it and it may hurt and irritate them.