Among old-time collectors there was such a prejudice that the cards often sold for far less than the cards themselves were worth just because of the signature. I always thought it was really cool so I happily bought lots of signed ones. Got some of my own signed too. When it was less 'industrial' than it is now you could even supply your own pens and ask the athlete to sign in a specific place and they would happily accommodate you. I did that with these two:
Gehringer was a mail-order and he still accommodated.