I cannot speak to his M&M census, but recently in his auctions Aldrich has been making up population numbers for 1st-3rd revenues and modern "reds" and "greens". Some of the numbers he uses to hawk his wares are laughable.
When the number of examples in my collection + the number currently running on
ebay = a number almost as large as or greater than his known population claims, I know it's utterly bogus.
It's made up marketing hype rather than any scholarly census research.
Do NOT fall for it and definitely do not base any bid amounts based upon those numbers. If you have questions about scarcity, ask them here (in general terms based upon Scott number if you don't want to give away what you are considering bidding on) and also do searches on
ebay, the PF cert search, and Stamp Auction Network.