They sometimes try to get around this by saying only a handful of people were really in on it, and everyone else just thought they were working on the real thing.
This is one of the more infuriating claims, and it has become rather popular lately.
It certainly belies a complete ignorance of how engineers, scientists and technicians think, work and communicate. And it goes without saying that it's a particularly nasty insult to their intelligence.
And how do you isolate those "in the know" from those who are not?
Every engineer who worked on any aspect of Apollo would have needed to be "in the know" because if they weren't, they would spot the bit of engineering that they know would not work and the game would be up.
Its a fairly established fact that as more people are added to a group that know a secret, the chances of that secret getting out increases dramatically... Watergate is a good example, only about a dozen people new about the break-in when it happened in June 1972. By September, the world knew about it. Even worse was the Lewinsky scandal... only two people knew about it... President Clinton and the woman he was bonking, yet it still got out within a year of the affair.
The HBs would have us believe that NASA and the US Government, with many times the number of people involved in Watergate or the Lewinsky scandal, who would have need to be "in the know", have somehow been able to keep a lid on "da twoof" for almost 47 years!!! This doesn't just strain credulity to the limit, it strains it beyond breaking point...it is simply impossible!