In my youthful days certain chemical inducements were freely available during RP's.... I'm older now and see how bloody infuriating it is to RP with stoned people...
EL
Damn you Sat-Nav, you and your directional Tyranny.....
I once roleplayed with a stoner. The GM was the least forgiving GM in the entire history of unforgiving bar stewards. The game ran very quickly (only lasted two sessions) and the stoner spent most of it making new characters for the ones he lost through a careless, lackadaisical attitude and taking smoke break when something big kicked off.
It's not just good stoners, you also have to have a good game for stoners to play.
If you're playing a game that sober people can't remember the rules for without referring back to the book, Champions, for example, then that's going to turn a passable evening into the most boring, frustrating snooze-worthy evening you will have in a long time. If you accept the calumet when it comes around that will just make it more snoozerific.
If you're playing Everyway or Hero Wars with cool creative stoners, that would tend to be amazing.