depends. if it's someone i love and trust, and am in a relationship with, then i'd assume we'd sorted out our boundaries. women are often more stimulated aurally than visually (i can get you the references, if you're really interested), and sometimes, that sort of "dirty talk" is a real turn on.
but choose with care - i had a... well, shaggee (cos he was too much of a twat to be a boyfriend) who chose badly (sounded like a really awful porn film), and i had to resort to playing very loud music during sex, so i couldn't hear the stupid git's pathetic (and "huh?"-inducing) witterings.
working your way up to something really lewd, eh, McJ?