Swearing can be worked very well into the narrative for a kick in the kidneys. It shouldn't be out of character though and it shouldn't be excessive. I doubt D:OS2 will have swearing and that's fine, it's easier to go overboard if you have swearing than actually making it evocative.
In one of the kickstarter videos they showed some swearing in game. The dwarf in the party approached a statue of some kind of dwarf killer or w/e and called him a bad word (I don't remember what it was). There's also going to be 'racism', which seems to be pretty, light, like when the dwarf calls the humans 'horse-face' or whatever.
