Most big secrets don't get to be kept. The big, world-spanning conspiracies don't get to continue. The bigger the scope, the harder it is to keep secret. Conspiracy theorists love to feel that they are on the inside, recognising the massive lies told to the entire world by an inexplicably powerful group of people. However, while it is possible for a large group of people to be deluded at once, and for that delusion to persist for a very long time just because nobody looked at the evidence properly, if your assessment of the possible delusion is that it persists because of powerful and deliberate lies, you're wrong, every time.
Basically, I'm saying that if the moon landings were faked, or if there were a second shooter on the grassy knoll, our best evidence wouldn't be photo analysis. It would be the leaks from several dozen people who got tired of keeping the secret decades later and came forward to tell the truth. The most hilarious thing, to me, about conspiracy theories is that all the conspiracy theorists are all sitting around buying each other's delusions and lies.
Mokalus of Borg
PS - Wake up, sheeple.
PPS - Where, in this case, "sheeple" = "conspiracy theorists".