I think it's bull. Sterling Sharpe comes to mind. He refused to sign anything and I later found out it was because he didn't want it being sold to the highest bidder. I remember finally catching up to him when I was I think 10 and asked "Mr Sharpe, Mr Sharpe!!! can you sign this please??" his response was he couldn't cuz his hands were full. One hand he had his helmet through his shoulder pads and his other hand had his cleats and something else. I of course offered to carry anything for him and he just smiled and continued walking at a brisk pace.
This was shortly before I learned of the greatness that is Barry Sanders, so Sharpe and Majik were hands down my most favorite athletes ... as I would have said it then 'in the whole wide world!'.
I still remember the devastation I felt. After trying so many times to get close enough to him to ask, I finally got there and was rejected.
I blamed Sterling at first, but as I got older I realized why and stubbornly understood. Which is partially why I dislike money so much, I strongly feel it ruins the true 'value' of things that should not have a price tag. Such as, autographs. It would have meant the world to me as a 10 year told to have his ink on my purple bordered '89 Score supplemental card of his.