Exercise can offset the effects of smoking as well:
Exercise can do a smoker's body good - Los Angeles Times
And here's how I believe the health effects are overblown. Smoking increases the risk of heart disease, nobody questions that. Being overweight also increases the risk, and nobody questions that. So when a 300-lb smoker dies of heart disease, which one was it? My belief is due to the moral warfare on smoking, this person's death is chalked up as another "Smoking related death." It's now perfectly acceptable to be a non-smoking zealot, but harboring bad faith toward overweight people is just not as morally acceptable yet.
We all know or knew a smoker who lived into their 80s. But how many 300+lbers do we know that do so? Not too many. I think, in this country anyway, the shit food habits are the far, far bigger public health epidemic than smoking.
And you're right regarding the moderation argument; Many more smokers smoke every day than McDonalds customers who eat McDonalds every day. I stick by my assertion. If you're going to sin tax the cigarettes, then McDonalds gets sin taxed too. If you only eat the stuff once in awhile, you won't really feel the effect of the tax now will you? Just as if you only smoke a rather benign pack a week or so, the tax will not hurt you as much either.