There will be errors with any service....my personal opinion is that PSA is the most respected among collectors but I'm not sure worthy of the title. In a statement you could say they are accurate and overall thorough. However, for specific players I'd feel much more comfortable with a few of the collectors verifying specific player characteristics. Their Loa may not be as recognized by the average collector and it likely will not increase the value as much as PSA but I find these to be much more accurate.

Just for a few examples of what I mean...
I've seen several bats with wrong years associated with bats.. I've owned a few wrongly detailed.

I can't even keep track of the number of errors I'vs seen on PSA letters as well. I've seen a few sloppy errors such as a name not matching the bat (likely cut and paste or used same template and forgot to delete prior name.

Also, recently noticed a bat in a recent listing that 2 years ago could not be confirmed as game used by the referenced player and was noted in the LOA with no grade.... but now has surfaced with a game used high grade and no mention of concerns previously mentioned in LOA. This bat is legit and the 2nd LOA is correct, I'd be interested in knowing the process and research that went into the correction.