I try not to kiss them too much and move on to other 'activities' just to distract them. It can be hard, sometimes, to try to ask them to rinse with mouthwash, or even offer a mint or gum. In my mind, this is just as important as any other aspect of physical cleanliness -- you know, when guys show up after being at work all day, sweaty, etc. However, some guys can be really touchy about this (tough!). It usually doesn't happen very often as I make a big point on my faq about personal hygiene and specifically mention breath.