I used to smoke about a pack a day, I have since quit, and while a cigarette when waiting for the food was a necessity and a smoke immediately after eating was great, never would I smoke during the meal. None of my smoking friends would do it either.
I just don't see how you could enjoy your food if you were smoking at the same time. Your tastebuds would be all messed up. As though they wouldn't be already from the rest of the days smokes I suppose.
Mia and Vincent smoke while the are eating at Jack Rabbit Slims but I don't think I have ever seen people do that in person.