Mkultra seems pretty plausible to me, at least with the science they had at the time. LSD was making huge waves in the psychiatric community, and many humint objectives like interrogation and brainwashing are inherently applied psychology. LSD was a breakthrough tool that laid the psyche bare, if only they could discover how to harness it.
Combine that with amoral thinking about the cold war and "greater good" and it's understandable, yet reprehensible, that they dosed prisoners and johns in brothels.
It's funny you mention that, because the first thing that crosses my mind, whenever I run across stuff like this, is that the people who perpetrated these things were probably nice polite folks who had friends, got along with their neighbors, were kind to their families, and held the door open for people when they went to the supermarket.
And then they went to work every morning and played their part in monstrous endeavors that—on coming to light—make the rest of us question our faith in humanity.
I don't doubt that some people who wind up doing these things are legitimately sociopathic. But I also have a disturbing suspicion that many of them were probably normal, and bought into the idea that drugging and blackmailing some random person played a role in defending America. What matters more—some lowlife from the streets, or national security? Sacrifices have to be made, etc.
Pretty much every atrocity I know of—while spearheaded by evil people—relied heavily on the ability of normal, decent people to rationalize what they were doing.
Combine that with amoral thinking about the cold war and "greater good" and it's understandable, yet reprehensible, that they dosed prisoners and johns in brothels.