Well I can understand the use of minced oaths like gosh instead of god and geez instead of Jesus in the event that you want to swear but just don't want to offend any religious people in the area... yet I still don't manage to catch my tongue around the more religious of my extended family.
I can't really see any purpose to other minced oaths like ruddy/bloody fudge/f
uck besides comical value. I mean I'm in the habit of using frack recently because I've been bingeing on Battlestar Galactica, not for any other reason.
Eff instead of f
uck is pretty desperate though - it sounds almost like self-parody when someone uses it.
I find it funny when people consider darn and crap to be swear words. And I find 'cuss' itself to be an amusing word - it's just an abbreviation of curse right?