If he's already been asked once and managed to clean himself up it's quite possible that he simply has no sense of smell and doesn't realise what an unpleasant experience it is to work with him. Perhaps if you start off by saying how much you appreciate the effort he made previously?
I can sympathise because we used to have a fairly regular visitor who whiffed so much the house smelled even after he'd left. In the end I ended up banning him (but not entirely for whiffy reasons). I can also sympathise with the whiffer because my feet are horrible and I wouldn't wish them on my worst enemy
but they get a shower every morning!