Social proof is the tendency to believe what most people believe. If an advocate creates the impression that "everyone knows" that someone is lying and covering up facts, there is a subtle implication that those who disagree are somehow flawed and lacking in credibility...Appeals to authority add weight to these persuasions. If one or more of the people affirming a belief is perceived as authoritative, e.g., a physician or a political leader, more people will be persuaded. It may matter little that the expert is the only one in the universe with that opinion, if he or she is the only one whose opinions we hear...Vivid examples -- especially dramatic case histories -- often influence judgments more than dull but more accurate quantitative examples...Confusion techniques can create perceptions of toxicity, injury, or disease. For example, illogical but eloquent rhetoric delivered with an air of certainty can create such perceptions if a few clear alarming phrases are woven into the message...Manipulators often try to control beliefs and actions by exploiting people's feelings. Inflammatory emotional rhetoric hardens attitudes against the opponent, and subtly justifies bending the rules to fight against the evil doer. Rhetoric that characterizes the opponent as a powerful bully (for example, that the AMA is persecuting "alternative" pracitioners) elicits a desire to root for the underdog, and provides emotional justification for bending ethical rules.
I have been doing some searching for good arguments against these conspiracy theories and I came upon this article. However, to me it looks more like what the US government was doing than what the conspirators were.