I wasn't calling you stupid, I'm sorry if that's what you understood. What I was trying to say was that trying to actually use something like amphetamine as a hallucinogen would be a stupid (and dangerous) idea.
But I agree that my post wasn't very helpful. I was thinking only about classical/straight stims (amp, meth, etc), but it's true that often stims and psychedelics do overlap (and a large number of them are based on the same molecular skeletons - PEA and tryptamine are the two that come to mind, but there are probably others). To hallucinate off amphetamine you'd have to take ridiculous doses, and the other effects you'd be feeling by that point would turn it into a definite bad trip, but when you look at things like MDMA and AMT, the line is definitely blurred. The "problem", I guess, is that these drugs are pretty crude in their action, so can never be all that selective. Most (all?) stimulants work by raising dopamine, noradrenaline and usually serotonin in various proportions, and some also directly activate postsynaptic receptors; psychedelics generally activate these receptors directly to various degrees, while many also act as releasing agents. Same neurotransmitters, same receptors, but activated in different proportions according to the drug. It gets messier still when you consider that activating a given receptor hardly ever only has one effect. For example D2 agonism plays a major role in producing psychedelic-type effects (which is why it was the original target of first-gen antipsychotics), but is also heavily involved in the activity of stimulants (and something like haldol will almost entirely block the effects of Ritalin or amphetamine). Then there's also the fact that everybody's brain is different, and that even hitting the same receptor in exactly the same way is never going to have quite the same effect from one person to the next...
IMHO, instead of trying to consider all the possible effects of a given drug, it's more useful to just categorise it according to the effect that's the most apparent to the majority of its users. Amphetamine primarily increases energy levels in its users, even if in some circumstances it can also cause hallucinations and decreased sociability ("anti-epathogenic" I suppose?); it's a stimulant. LSD's immediately obvious effect for most people who take it is to produce hallucinations, although many find it stimulating to a lesser degree and some people report dissociative effects (though that's probably a bad example, since hallucinations are also a detachment from reality :-/ ); it's best to just consider it a hallucinogen.
