I only smoke pot about 4-5 times a year, if that much. Basically, whenever someone hands it to me. Being such an infrequent user, I'm not much into getting completely raped by the aggressively potent shit some people smoke these days (which I attribute to people's growing over-indulgence, tolerance and dependence on pot, not the development of "better weed"). I don't like throwing up, sweating profusely and getting CEV's for hours from taking a few hits of marijuana, having such low tolerance to some of the ridiculous monster-weed that's out there these days.
Point is, I don't smoke enough for it to make a difference. Just a puff or three or four, or a couple of bong hits and I'm done, thanks. But I have very much enjoyed the occasional spliff (which, at least where I live, is tobacco and weed in a joint). Most people scoff at the very idea, and obnoxious hippie fuckwits usually whine about how "tobacco is poison, maaan, blah blah blah" (as if inhaling combusted plant matter of any kind is especially "natural" or "good for you"), but I enjoy it, because I get a nice mellow/non-aggressive marijuana high with a slight nicotine buzz to go along with it. It's the best thing I've found for social smoking. I can trip balls or get stoned as hell on my own and enjoy it, but getting high in public just sucks for me because of my anxiety. In social settings, a spliff allows me to achieve a mild, pleasant high, instead of getting completely freaked out.
I have a stoner friend in Germany who says he does not like to mix tobacco into his weed. Perhaps being a stoner has something to do with that. As for Americans, even casual smokers (not raging stoners) in the US tend to smoke only pure marijuana. It's cheap and easy to obtain. I think the average smoker in the US only "resorts" to spliffs in an effort to stretch out their herb. I still like them, though. People can scoff all they want. I'd rather be a lightweight than a shiftless burnout stoner who treats getting baked like a competition, to be honest.