Smoking doesnt actually affect your voice that much, even if youve been doing it for years.
What it affects is your LUNGS which are responsible of most of what singing is about.
I dont know if Scott makes any kind of excercise before/after singing, but as a former classic singing student, i can tell you that no matter how fucked up your voice can be. You can smoke 20 cigarrettes and drink half a bottle of any liquour.. AND HAVE A FLU.
But with the proper vocal warming, you can still perform amazingly.
I am currently studying classical singing...and I have to disagree on that...smoking is always a "no no" when it comes to singing, mostly because of your lungs, like you said, but also your vocal chords, it gives a "raspier" sound and makes you lose high notes on the long run. And alcohol dries the chords up, and of course if you get "cheerful" you might also lose control of your breathing, so it's never a good idea to drink before singing.
I agree with the flu though, with proper training you can sing perfectly and not be able to speak from the flu, and things like that...
Of course it can be done, but you would achieve much better results without any cigarettes or alcohol...also physical exercise helps (which Scott did a lot of before but seems to have abandoned now, although that is pure speculation on my part).
From what someones who went to the Christmas concerts said (I don't remember who), Scott does indeed warm up (they said they could hear him do it while waiting), and he also said himself that he does about 45 minutes of vocal exercises when he has shows (he should be doing that every single day of his life so as not to lose anything but I have no idea if he does it or not).
The thing is that he had problems in his vocal chords, probably from straining them too much, maybe from the constant touring, or improper technique, who knows...but if he indeed has scaring in his chords like the medical report said (it actually said "likely" but did not confirm), well that's definitely not good, that also makes you lose some of your higher range, from what I've read.
Sorry about the long post, but I'm really passionate about singing and the voice
