Being rude to someone is being rude more or less regardless of reason, it's just not right. Even if I massively disagreed with something about someone, I wouldn't stoop to abusing them randomly.
I personally will admit I have a particular dislike of smoking, mostly because tobacco smoke makes me feel sick pretty easily; I'll put up with it when I need to, but avoid it where possible. Smoking probably (though it's hard to estimate) makes the government more than it costs them, so I can't argue on a social-financial basis against it really. For me, as long as smokers take care with their effects on other people (particularly avoiding smoking near children, preferably including their own) then it's their choice really. As I say, abusing people randomly for anything like that is just stupid though.