I dated a smoker once, because I thought that I could overlook it. But I was wrong. It ended up being one of the biggest issues in our relationship. He always smelled terrible (from the smoke), and kissing him tasted gross. It made him SO much less attractive to me.
Smoking is a deal breaker, my grandfather died of lung cancer last year after being an avid smoker for years. He suffered with the cancer for 15 years, 7 of those years it was very aggressive. Wouldn't like to go through with that again, especially not with a spouse. It's a disgusting habit.