I wouldn't. How can I take motivation and health advice from someone who is addicted to one of the worst habits you can have? If the trainer can't keep himself healthy, why would I want to take his advice?
One of the trainers in my gym is obviously a smoker. He comes into the gym stinking of cigarettes. Nothing like getting a strong whiff of that as I'm trying to squeeze out those last two shoulder presses.
I'm not trying to start a debate on smoking vs lifting because it's been done to death here.