It just seems fascinating to me that the museum says 100% fake, and in the "Strange Inheritance" episode swarmee posted above, at the 15:40 mark the host asks Steve Grad how sure he is that it's authentic, and he says 100%. No leeway in those opinions. So somebody has to be 100% right, and somebody has to be 100% wrong. And both are considered to be experts in the subject matter. I am neither an expert on Joe Jackson nor his autograph. But based on its scarcity and his known struggle with signing his name, I can't see any way to say with absolute certainty that a purported Joe Jackson signature is authentic (excluding the very obvious fakes, such as on a Bud Selig ball). Maybe someday in the future there will be a way to isolate DNA or a fingerprint on a 100 year-old photo that's been handled by many people. But I assume that the person who spent that much money on it did the research and is satisfied with the purchase. The trimmed Wagner sells for millions, despite everyone knowing that its trimmed.
In trying to find out more about this topic, I found this interesting Joe Jackson item on eBay. Maybe the seller is a member here. But apparently Joe practiced signing his name before placing a signature, and this is a piece of that practice attempt. So maybe his signature varied based on how much practice he got. In any event, after the sale price of the signed photo, maybe this is now a good bargain:
https://www.ebay.com/itm/14272455219...AAAOSwpixarEdm