Correct, but some people are rejecting every conspiracy theory on the sole ground that it assumes conspiracy, and this heuristic is not critical thinking.
If they can't do that, their "theory" isn't worth my time. Now if one of the crazies keeps bugging me with his theory, I might apply critical thinking to shut him up, if I don't lose patience and punch him in the face first.
Conspiracy theorists usually show a strong belief in something pretty improbable without a shred of tangible evidence. I think it's fair to label them as "crazies" because they tend to be very vocal about it and impervious to logical flaws in their own theories. And they're annoying, when you annoy people, you can expect some kind of negative feedback, like being mocked or called names.