Comment by snickerbockers

IDK about PSA specifically, but I've collected comics, video games, toys, etc and the one commonality between all of them is that there are these big "grading" companies that charge money to seal your stuff in a plastic box with a label at the top that indicates its "grade" and there is always a scam of some sort. Sometimes they're not actually investigating the goods with any real scrutiny, sometimes they have a conflict-of-interest involving a well-stocked seller, sometimes they're directly manipulating the market. There's always something with these guys.

Also a lot of their income comes from convincing people who aren't educated on the market to grade extremely common items that will never be worth any significant amount of money no matter what "grade" they get; not actually a scam in that case but it shows you what their real priorities are.

I've also seen them set up booths at sci-fi conventions where you can pay to have them "authenticate" things you got signed by celebrities. In this case the authentication is entirely separate from the signature so there's nobody who can actually testify that they witnessed William Shatner signing your crap, only that they know your crap and William Shatner were in the same convention center at the same time.