I think I sound less intelligent when I swear. It sounds forced, Srh can attest to that. And then I filter myself with "What the eff" and it sounds even worse, so I just say balls and tits. If I'm going to sound unintelligent might as well make a few people do a double take.

Everyone has their opinions on what makes a curse word, and everyone settles on words they deem okay to use in polite conversation. If you're censoring yourself, even if it's just replacing "smurf that" with "screw that", it has the same effect and everyone knows what you're getting at, so there's really no harm done, unless of course you're talking with a person that thinks saying "crap" is bad too. *shrug*