I see a couple other threads that point this out, but let me be clear: there is no controversy. There is a myriad of evidence that Benson never even got any smoke in his lungs, or if he did it was a minimal amount... and he didn't hold that amount in, like you're supposed to.
My theory is that Benson pretends to be a pothead to excuse his utter idiocy. I mean, a 980 on the SAT is bad.
Evidence:
1) He pulls on joints like they're cigars. He "puffs". You can see him pulling with his mouth rather than with his lungs, and then he puffs out his cheeks to apparently hold the maximum amount of smoke in his mouth. As a result, his exhales are tiny and the smoke is still thick (rather than diffused by the lungs and additional air used to fully inhale). I have doubts Benson even knows how to smoke a cigar, because his drags were just so SMALL!
In fact, there is never an excuse for puffing out your cheeks like that, no matter what you're smoking. That's not how you take a drag off of anything.
2) He smokes pipes the same way. He works up the smoke, but is never shown doing more than puffing.
3) He goes through the the vapor bag too slowly, and his exhales are, again, small. He doesn't realize the main use of the bag is similar to that of a gravity bong: to force the maximum amount of product into your lungs.
4) He blows out the vapor without inhaling it every time. Vaporizers are actually very ineffective when they are not held in the lungs for several seconds, which Benson never does. The vapor is also much thicker right when he begins blowing, while normally when you pull vapor into your lungs, the exhale is consistent and not very thick. When you pull vapor into your mouth, that's when you get thick clouds and rings right away. When he blows vapor in Silverman's face, it's clear he didn't even inhale it. It's as thick as smoke.
5) He has no concept of the difference between indicas and sativas. This is extremely rudimentary pot knowledge; anyone who has ever bought pot (much less quality pot like California has always had) knows the difference. Maybe he was playing dumb for the camera, but he really did seem like a middle-aged man encountering pot for the first time.
6) What kind of pothead exhales the way he does? He blows it through a tiny hole in his lips and never alternates, and sees smoking pot (or vapor) as such a novelty that he was even blowing it in Sarah Silverman's face. I agree with her response: that's what idiots do with their cats. Hardly even looked like he tasted the pot, because nothing went through his nose either.