I'm totally falling into agreement with the "time and place" thing. When I meet someone for the first time, I talk very civilized and watch how the conversation develops. If the other person starts using profanity, I loosen up and use the minor ones, that way he/she might feel a little more comfortable instead of maybe thinking "I wonder if this swearing bothers him?" Then again, they probably don't care or they wouldn't be doing it in the first place. But I'm going to tell you right here and now....I'm a truck driver, and I INVENT new curse words every day. If the general public could hear some of the conversations I have on the CB radio, parents would be poking their kids' eardrums out with sharp objects to alleviate the pressure.
Now, when I come to a place like this that specifically asks for no profanity, I don't consider it a violation of my right to free speech. They're asking a small favor...please be polite and respectful, and I do just that. I can make your ears bleed in half a sentence, but is it necessary? No. Why do I do it then? Good question. Nobody ever commends me on my skillfull weaving of profane tapestries. Just a bad habit, I guess.