A friend of mine worked as a nanny. Employers asked if she was a smoker, she said no. Ok, all fine, she worked for a month or two. All fine. Then one day (her day off) her employers noticed her outside a pub having a cigarette.
So they fired her -- as she lied to them therefore cannot be trusted.
But really... If she never smoked on the job, what does it have to do with employers if she lights up socially in her free time?
Myself i'm a social smoker. I have a pack of fags in my handbag, but i maybe have one twice a WEEK, not more. If a job required non-smoking, would i be a liar if i applied?