actually, this isn't true at all. i honestly don't understand why ppl think everyone who smokes pot is a walking cheech and chong video. sure, some ppl you can tell once you know them well enough, but in my experience the only ppl you can tell are the one's who don't care if you know and are just having fun being ripped goofballs.
my best friend of 11+ years has run the gamut from 24/7 stoner to smoking a few times a week to relax. i know him better than his own mother and to this day i can't tell for sure if he's stoned unless he tells me or i see him light up. when i smoke, i tend to be silly and goofy but that's only if i feel comfortable doing so. when going out in public it's pretty easy to act normal. nobody in my gym knows when i do or don't smoke because i don't make a spectacle of myself. it's just like any other adult having a couple beers and still managing a mature conversation.
that said, i usually don't smoke before rolling. weed can push me a little towards the anxious side sometimes, and unless i'm sure i'm in the right head space, i tend not to risk it. i've had some really amazing rolls while stoned tho. i felt totally relaxed, never seemed to get tired, and didn't have to think as hard. in fact, mj is bad if i need to have focused, methodical thought. i tend to function more on instinct and intuition -- and i'm much less phased when i make mistakes --which is why i think my rolls are better.
for the record: i smoke much less than what most ppl drink. and i drink much less than even that. i enjoy substances, but i'm a lightweight -- and i like it that way.
cheers!