It depends on the frequency of the swearing. Guys or Girls who say "eff this , eff that " every word is almost a swear, then it's rude and quite embarrassing. A little swearing usually does not matter, it depends on who you are with, some people are really weird about it and are offended by it, so once someone else swears you'll know if you're in the clear.
Also, NEVER ever swear around your girlfriend's parents! That's a huge no no and the girl will usually be traumatized