Like the OP stated, there are a handful of players who wouldn't/won't sign SSPC cards because they weren't compensated. I don't have a full list, but it's definitely a handful.
I think this belief stems from the rule that prevented attendees of his basketball fantasy camps from bringing Fleer cards as their item to get signed. Realistically for the longest time that was the best way to get a specific item signed. He doesn't do paid signings, he's not approachable in public, and anything he does sign under contract is UD related. I'd bet 90% of the non-rookie Fleer, Hopps, Topps etc signed cards I've seen date to his time with the Barons as that was the one time he was great with larger groups. Most of the signed RC's I see are more modern signatures probably garnered at golf tournaments, the MGM, or the Arena where small groups get access to him.
Here's some tough signed cards not mentioned yet to get from living signers. Sadly most aren't mine. I just track them as I see them.
Someone stated Steve Garvey won't sign his 1982 Fleer card. I've seen one I felt was authentic then a couple years ago someone picked up a raw example on eBay and was able to get it in a PSA/DNA holder. I didn't fell comfortable with the card though. At one time I was working on that set signed and knew I probably get the Garvey so I got creative. I eventually broke up that near set, but I kept my Frakengarvey.
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Then of course, there is the living legend himself....
