[billmalarky]

It doesn't matter if it's a secret or not. Constant exposure to lies can change perception even in highly rational people. Critical thinking takes effort and nobody has time or energy to digest every bit of information that hits their brain. Slowly but surely people begin to subconsciously accept the lies.

This is why propaganda is so effective. It doesn't have to even be convincing to be successful so long as it is pervasive.