they should do it with aplomb 
Not that we're bad at swearing here, you understand - I love words like twunt and wankbadger. In fact, that whole swear+woodland creature formula is brilliant. Its just that we've been rewatching Firefly and I love the way all of the swearing is done in Chinese.
Go se
go niang yang de
etc.
I think that using foreign swear words will take things to a whole new level, after all, foreign words are classy and we have a reputation for something or other (can't remember what).
To help people decide which swears to include in the Mumsnet lexicon, if we should go with swears from one language or mix and match, or even if our own swears are so good we don't need to look at furrin ones, I include a handy link www.youswear.com/
So aibu?