I am one of them. I rarely got hangovers and I'm not lying. The reason why or so I believe is the type of drinks I drank. I drank everyday to pass out first of all so my tolerance was high. My drink was always ONLY wine or it was chambord and vodka on the rocks...not juice or water added. For wine I would have at most a bottle and a half a day or anywhere from 6-10 vodka drinks...whatever it took to pass out.
I found that if I drank rum and cokes or something like that, I would get a hangover. But if I stuck with the straight liquor with vodka, I didn't. Not to say that wine and the chambord drink didn't have sugar in them, but there was something about drinking things with coke or sugary martinis that seemed to do it.
I didn't get hangovers but in time, things did catch up with me. I got really really tired after a few years of not one single sober day. But that was because my liver was getting sick.