Even later to the party …
I don’t have a problem with swearing, as long as it’s relevant to the character and important as dialogue.
The thing to remember, in my mind anyway, is dialogue in a novel is never realistic. It has to attain the appearance of being natural, but will never be a verbatim mirror of the big bad world outside. And the words on the page are a condensed version of reality from a reading perspective. What I mean by that is, for example, if a character says ‘fuck’ every three pages, it’ll seem a lot. Whereas in real life we may well be saying ‘fuck’ several times a day.
For the record, occasionally, my main protagonist will say ‘Fuck. Fuck. Fuckity-fuck fuck’. But that’s just the way she is. And she’s probably just found a corpse.
(As an aside, I think I picked up that particular phrase from Three Weddings & A Funeral :) )