If there are narcotics in the game then............

[Rexx Shredd]

....how come we dont have more strung out NPCs?

[Pablem]

Rexx, I see them all the time, but the symptoms are extremely similar to being in the presence of your worshiped hero. (glazed eyes, swooning, unintelligible screaming, being passed out, etc) So you may have trouble identifying them.

[Darakhoranon]

As Pablem said, it's nearly impossible to tell whether a given NPC is just stoned or paralyzed by your divine awesomeness, Rexx. Sure, the aftereffects are much, MUCH worse if said NPC is on a "RAT" (Rexx Awesomeness Trip), but that just means you can tell AFTERWARDS. Still no luck differentiating between narcotics and your presence while they're in effect...