As Bill Hicks points out, you couldn't pay me to be a non-smoker.
Though I only smoke on rare occasions - and usually only at clubs where the atmosphere is smoky anyway - i could never be the kind of person who judges a personal choice. And fine, maybe second hand smoke is bad. But it's probably worse for you if you've just come all the way over from the other side of the room to cough pointedly at me, isn't it?
I always just say "Gee that cough's bad - it's lucky you don't smoke!"