The way I look at it, the Soviet Union would have been closely monitoring the moon landing. If they had a reason to believe that it was faked, they wouldn't have hesitated to say so.
While the moon landings obviously were not plastered all over the news media, the Soviets almost universally, although quietly, praised and congratulated the astronauts and NASA on their achievement.
If the landing was faked the response would have been drastically different.
Back in the day there was a lot less information available for everyone, yet today this seems more likely to happen.
I kind of wish these vast multi-national conspiracies that can cover up important world events, and maintain the secret for decade after decade existed. Who wouldn't want to work for such an organized, well funded, and culturally diverse organization?