I don't really like swearing. Expletives very, very, very rarely come out of my mouth, or get typed on the keyboard.
My more proper excuse is that there are just so many different words in the language that can express intensity, fear, anger, seriousness, and disbelief. It doesn't have to resort to foul swearing to make a point. And sometimes, it's the simpler words that cause a deeper impact than liberally sprinkled verbal bombs.
On top of that, I just simply find it weird to swear. Whether I type it out or say it out loud.
It just doesn't sound like me. The few types of people I associate swearing with include aggressive people, crazy people, brash people, and physically hyperactive people. And as far as I can tell, I don't think I'm any of those.
When in pain, I don't even reflexively swear. I can't. I'll probably groan, moan, utter a few oohs and arghs, but not much else.
When frustrated, I'm hardly ever bothered to swear. I'm usually too distracted by my own frustration to take the effort to think of how to express that frustration in words.
So in the end, most of the words that come out from my head are clean.
Not quite the same going in though.
But it doesn't matter if I can keep my output purer than the input, I guess.