Post-war baseball cards are unlike art or real estate due to the trust in third-party graders for their value. If people lose faith in the grader's ability to accurately differentiate an 8 from a 9 then the values could drop significantly. This loss of faith could come about if people found out that cards could be resubmitted and get different grades, that certain dealers got preferential treatment, or that graders make mistakes (imagine the outcry if the most valuable card in the hobby turned out to trimmed after passing third party grading
). I would suspect that if a reporter ever decided to run an experiment where they cracked 10 cards that were graded mint and had some independent hobby experts review each one and then resubmitted all 10 cards to the original grading company, the grades would be alarmingly inconsistent.
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