In other fields a cert stating "we decline to render an opinion" does occasionally happen especially on very rare items.
And the experts when confronted with evidence showing that an earlier opinion was wrong will correct the opinion.
A writeup of an item accepted as genuine since at least the 1950's.
https://www.rfrajola.com/opinions/klep.htm
And the auction listing that prompted the examination. (Lot 68)
https://siegelauctions.com/lots.php?...r+8-10%2C+1998
Yes, experts will make mistakes, but real experts fix them when they're wrong. And are wrong a lot less than PSA etc on expensive items.
For some reason our hobby generally accepts an opinion from some experts as written in stone, and the companies do the same.
I'm unsure about the Jackson photo, but am inclined to think it's not his signature.
For a million plus, I'd want way more convincing than "well, PSA says so" And to be entirely clear, I believe the hobby in general deserves better than that.