There have been no surveys on this, but over the last couple of weeks telling friends of my housemate's cancer the first word out of all but one person's mouth or on the email is "shit". For those that don't know after surgery she is doing well in body and spirit.
Even the most ladylike of friends have reacted this way.
I had a professor who used the word f--k the was most people use the verb to be. It was a word that would send my birth mother into spasms. I have to admit when I was at my wits end with her I would use it. Not nice I know, but self defense is sometimes necessary.
Mostly I don't swear, but not from remembered admonishments from my grandmother on the importance of always being a lady. When one doesn't ordinarily swear, when one does boy it is ten times as effective.