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.

I don't think it's an overt scam, but let's put it this way: as with auction houses, there is a disconnect between the service the company is providing and what the buyers think they're getting. And the companies have no special interest in correcting that.

For grading companies and for auction houses, the goal is to move the highest possible volume of goods at the highest possible valuation. They're not going out of their way to root out non-obvious fraud. They operate with the assumption that 99% of the traffic they're handling is legitimate, and of the 1% that's forged, only a small fraction of the buyers will ever find out. On the rare occasion it blows up, they can apologize and settle for an amount much less than what it would take to investigate every specimen with great zeal.

From stories of same exact card being graded for different ratings at different times. Would indicate that they are less perfect in their service than they might market. Difference in grade can change the value.

So as whole the process is quite questionable at times.

Not to even talk about some things slipping through or being questionable in documenting.

Something can be subjective, without being a scam.

Are you suggesting they are deliberately misleading people, or are you saying grading is not consistent and is subjective based on circumstance around when the item is graded.