My answer to the OP...
It gets annoying when I think the person is cussing to make her/himself look cool or tries to fit in with a certain group.
That's when the person looks like an idiot.
I'm tempted to tell that person to grow up already!!!
I am guilty as the next person of swearing, especially when I'm really angry about something. However what we say and HOW we say it is a reflection of ourselves.