people's heads would explode of they knew what kind of crap goes into most cigarette tobacco. the good stuff is used for cigars (american cigars aren't anything to write home about either), pipe tobacco, and higher-end cigarettes like American Spirit. the normal 'class A' cigarettes use the lowest grade, and often scrap, tobacco....at least as far as I understand it. there's all kinds of chemicals added to make it taste better, sulphur to make it burn better (ever see a tiny cigarette 'flare up' as someone is holding a lit cigarette? that's the added sulphur), etc.
as an unrelated side note, thanks to the new vaporizers, (like an e-cigarette on steroids) I have gone over 5 weeks without a cigarette after smoking for 39 years. I'm starting to feel a hell of a lot better, and both my doctor and my cardiologist are happy with the change, saying that the nicotine isn't my health worry, all the bullcrap I'm no longer inhaling in the cigarette smoke was.