The stereotypical pothead is a lazy dreamer, with the attention span of a gnat (NewScientist, 21 February 1998). He has difficulty following complex ideas, he laughs at things that no sober person would find amusing. His eyes are dull and hooded and his voice is hoarse.
Like almost any stereotype, examples are easy enough to come by. Just look at that group of guys over there, who've just got back from having a session in the gardens across the road from university (this group includes me, btw). They're sitting there staring off into the middle distance with veiled eyes, occansionally looking at one another and grinning or spouting some garbled piece of pseudo-wisdom and croaking a collective 'hur, hur'. That's what stoners are like, see? Or look at Magenta's roommates here, or cantsin and kaytay's descriptions here, also psykelus' piece here.

Hello, this is reality calling, can I speak to your supervisor? The people you're pointing to aren't just stoners, they're, well, stoned. They aren't focussed on you because of the party in their heads (to which you've no doubt turned down an invitation). They're laughing and misinterpreting because every word you say fits into their thoughts in a complex and personal way - they're high, goddammut! The drug has slowed their production of saliva, dried out their eyes - hence the hooded eyes (for protection from the acrid atmosphere of tobacco smoke) etc. They're acting spacey because, frankly, they are.
In a couple of hours they'll be back to being sharper than you are.
Let's go down one floor to the campus bar and apply your logic to the crowd that has already gathered there at 3 pm on this friday. By the reasoning that led to the above descriptions of potheads, the typcal drinker is loud, obnoxious, uncoordinated, stupid, prone to slurring their words, violent and inconsiderate. Or maudlin and introverted.

If you're going to node about 'stoners', then please think about whether you're talking about stoners proper or just people who are in an altered state of consciousness. Pointing out people's differences is rarely particularly clever observation, especially when you generalise in such stupid ways.

A result of me being sick of certain assumptions routinely made about me.