The ability to metabolize alcohol is interesting, some people have it, some dont.
Ive known heavy drinkers/alcoholics who have never had a hangover in their life. If i could drink like a fish and feel great the next day, i can see the trap some could fall into. I am out of commission for a day or two if i get really hammered, i rarely do that anymore.
I know one thing, sweating-exercising heavily the next day does cure a hangover.