It's interesting to note in the case of wine the extent to which smell and taste are mutually implicated in creating perception of "flavor." I've frequently read that much of what one perceives as taste in wine is actually "smelled" in the sense that the vaporization of alcohol in the mouth allows for olfactory receptors to pick up smells through the "back door," so to speak. Which is no big surprise considering how we actually go about tasting wine, swishing it around in the mouth, etc.

In the case of smoking cigarettes, I'm sure it affects your ability to smell (and by implication of the above, to "taste" wine), but I think tracking down exactly how much would be no easy task, without some systematic experimentation involved. But even to do so would assume that such questions can easily be removed from a moral and political climate that has recently come to surround the practice, and that any "answer" to the question could every be unproblematically offered outside this political realm. The politics of smoking are undoubtedly exacerbated among serious wine drinkers, since so much care goes into perfecting the ability to perceive the minutia that can be discerned from the glass.

All that said, I personally think that if you wanna drink wine and smoke at the same time, you're best not to pull out your well-aged Barolos--but if you do, make sure to stay away from the guy at the next table who does have his nose inside his own well-aged Barolo, because he'll probably understandably punch you in the face!