This isn't memorable in the right way, though, to be an effective conspiracy theory. When do I think of it? Only when I'm thinking about the topic of kooky conspiracy theories. Nothing I see in my daily life, on the news, etc., ever makes me think of the Brain Bank Cities on the far side of the moon. The illusion of constant confirmation is missing.
An example of an effectively memorable conspiracy theory is the idea that Donald Trump is secretly a white supremacist and communicates this fact through "dog whistles." Once you've heard that, anything Trump does or says that has any connection to race or immigration makes you think of it and creates the illusion that the conspiracy theory is relevant and therefore probably true.
Here are two more examples of conspiracy theories that I find to be effectively memorable despite the fact that somebody just made them up.
Utah no-fly zone: If you plot all reported UFO activity (sightings, crashes, abductions) on a map of the US, you will find that they occur all over the country -- except within a radius of 200 or 300 miles of Salt Lake City. Extend the radius by another 200 or 300 miles, though, and you have the majority of all UFO activity in America!
Antarctica: The Nazis spent a lot of money in Antarctica for unknown reasons. Today, many world leaders travel there once a year.
I think part of what makes these effective is that they aren't properly conspiracy theories -- no explanation is given of why UFOs won't fly over Salt Lake or why powerful people make regular pilgrimages to Antarctica -- but just assertions of (made-up) facts that fit a pattern. Once you've heard about the pattern, anything that "fits" seems to confirm it. Any UFO stories out of the American west, for example, will make you think, "Hmm... kind of close to Salt Lake but not that close" (the vagueness of the two radii is helpful here). Any celebrity saying anything about Antarctica reminds you that they're probably secretly flying there once a year.
Maybe Francis E. Dec was wrong, and the Brain Bank Cities are actually at the South Pole!
