I hadn't seen your three last paragraphs when I started answering you.

A predictable hyper-suggestibility outcome out of the use of a particular psychotomimetic substance supposedly does exist with the consumption of scopolamine:

The effects of scopolamine were studied for use as a truth serum in interrogations in the early 20th century, but because of the side effects, investigations were dropped. In 2009, it was proven that Czechoslovak communist state security secret police used scopolamine at least three times to obtain confessions from alleged antistate conspirators.

This is how I first heard about it:

World's Scariest Drug (Documentary Exclusive)

VICE's Ryan Duffy went to Colombia to check out a strange and powerful drug called Scopolamine, also known as "The Devil's Breath." It's a substance so intense that it renders a person incapable of exercising free will. The first few days in the country were a harrowing montage of freaked-out dealers and unimaginable horror stories about Scopolamine. After meeting only a few people with firsthand experience, the story took a far darker turn than we ever could have imagined.

I think psychedelics are like ''conspiracy theories'', you can't put them into a single block as all being the same without the risk of creating a straw man argument. So yes, I agree with some conspiracy theories probably being used as a disinformation tool to spread cognitive dissonance, and with some others fitting in the urban legend category, while the rest must be falling in line with the where there's smoke, there's fire idiom.