When my son was a batboy and clubby at the Arizona fall league about a decade ago one player- not a star asked him to autograph all is fan mail for him. I posted that on sportscollectors.net and people laughed at me but his mail was being ghost signed.
There is alot we do not know. Not sure which of my Sid Luckmans are real if any.
I have never knowingly sold a fake. I would though be tempted to sell one I thought wasn't real if it is slabbed.
When I was a kid and I stalked players at the hotels in the 1960's I used to copy players signatures for fun. never sold any. As a result my own signature has probably 4 or 5 versions with hybids incorporating different parts of each style. It would be about impossible to judge mine.
Also awile ago my son was a big Clint Barmes fan and we bought the giant banner of him that used to hang at Coors. We had Clint sign it and his autogrpah was nothing like we have ever seen him sign before or after- giant well formed distinct letters, etc. Even the best authenticators of us and others out there have a probably 10% margin of error or more.
I have a Ned Hanlon that matches no exemplars I have ever seen but has impeccable provenance and got it from Jimm Stinson who is as good and honest as they come. Sometimes I am tempted to sell it just cause it doesn't match.
Look at these two David Newhans
http://www.ebay.com/itm/2004-BOWMAN-...item19c0590c9e
http://www.ebay.com/itm/David-Newhan...item4d0b7b178e
I have over 50 David Newhans and he is a friend of mine. Look at the differences especially the D. I have watched David sign a stack of cards of mine and gotten both of these styles from him in the same batch in a random type order. Before I saw him do it I thought one was wife signed.
Sometimes I think if someone offered me a million dollars for my collection (I have alot more I haven't posted) I would just take it and buy a nice condo in Hawaii and stop pulling my hair about about judging authenticity. other times I am too addicted so even if someone offered me 1,000,000 just for my Hugh Duffy signed Mayo Plug- I would turn them down