The clincher for me is that those of us who know that Apollo really took place, know that it is superbly documented in the intricate scientific and technical details of the Manned Space Flight procedures, manuals and design schematics, involving hundreds if not thousands of contractors, and hundreds of thousands of people, starting with the Mercury program, through Gemini to Apollo, and beyond into the STS programme. Manned Space Flight has to be one of the most extensively documented programs in the history of humanity. There is only one story throughout, consistent within itself, verifiable at every step, and able with withstand the most minute scrutiny.
The conspiracy theories on the other hand, are many and various, often conflicting with each other, are not verifiable, and they simply don't stand up to any kind of scrutiny. Not one conspiracy theorist has so far been able to document a candidate scheme, a plan down to the fine detail required, for exactly how the Apollo moon landings were supposed to have been faked. Plenty of innuendo and unproven theories... but NO FACTS!