Depends entirely who I am talking to. If it's women, swearing is a terrible thing to do. Some friends I swear like a sailor around. Other friends I refrain from swearing. I also swear all the time with my dad, not so much with my mom.
Be quiet, I bet I swear more than you. I swear a lot. I'm often castigated for it by ridiculous people; 'do you think it makes you sound big and clever?' no, love, it's just how I talk. I'll drop in the F word when I'm looking for something else to say or I can't articulate exactly what it is I'm getting at. When really someone pisses me off I'll devote a couple of seconds/minutes/hours to the subject of them, for example, screwing his sister or receiving a blowjob from a goat and my views on this act. When I've injured myself (catching fingers in doors and stubbing toes, usually), it'll be much less eloquent; usually something along the lines of FUCKING FUCKING FUCK OW FUCKING CUNT FUCK FUCK FUCK SHIIIT.
This doesn't mean I swear (much) in front of my grandparents - I'll often call something 'bloody awful' in front of them; parents I swear a fair bit with, little brothers; the nine-year-old I'm quite free with my mouth with (he's heard it all in the playground) but the six-year-old I'm much more conservative with (since he's still at the stage of calling someone a lady-dog when he wants to call them a bitch.)
Edit: oh, and it still means a hell of a lot when I swear directly at a person; usually I'm swearing to describe something or someone, but I'm quite shy and very anti-confrontation, so if I stand in front of you and call you a cunt then I really, really mean it. If, however, I use the same word in jest, which is fairly frequent in my friends company, it's obvious. Context is everything; just because I use these words regularly does not make it any less meaningful when I'm using them seriously.