I can honestly say that I never heard my Dad swear. He had alot
of strange "codewords" though (to this day, I don't know what 1/2
of em mean). My mother was an elementary school teacher, educated
through 12 grades by the School Sisters Of Notre Dame, and didn't
even allow the use of slang in the house, so I think Dad knew better
than to use any expletives. Even if Helen wasn't around, his kids might
blab.
Like "The Old Man" in "A Christmas Story", my father was always at war with
the furnace. You'd hear all manner of clanking & what sounded like muffled
swearing 
coming up through the hot air registers. Ma would open the cellar
door & yell: "Frank!" and you'd hear "Huh? Helen, I'm fixin' this thing down here.."
and the clanking & muttering would resume .
The Darren McGavin character in that film reminds me alot of my Dad. His war
with the Bumpuses' dogs next door and when they steal the Christmas turkey
while "the Old Man" is reading the paper! If anyone ever stole the turkey dinner
in MY house, my father would've given them the death penalty & impose the
sentence himself without further ado! 
m2