Conspiracy theories are not "questioning popular opinion". You can question popular opinion without coming up with crazy theories, or at least, you should take them as what they are: wild guesses at what might explain some discrepancies in that popular opinion.

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.