How close is difference between theory and conspiracy, if the main actor does not want you to know something? One of the strategies can be to completely poison

How close is difference between theory and conspiracy, if the main actor does not want you to know something? One of the strategies can be to completely poison information, as you said "label". In that way it would be hard to distinguish between "true" and "untrue", and in that way basically force researchers to even approaching subject. In that way only person from inside could uncover truth... I guess ... And this is same problem like with corrupt government, if they hold all the keys it is very hard to overthrow dictator, as it is very hard for truth to surface out.