if you're not weak and get addicted, I think smoking can be healthy in limited amounts, I smoke 1 pack a week for 2 months while cutting, that totals 8 packs a year, during this cardio is performed and this reverses any negative effects on lung capacity. caffiene and nicotine is thermogenic, and nicotine has nutrient partitioning benefits.
it also as some mentioned causes appetite supression, which can help with cutting if you've just come off a massive bulking cycle and are use to shoving mountains of food down your neck.