team signed ball question

[sportscomicfantasy]

So I have many signed balls that I have gotten over the years, mostly baseball but a collage of all different sports. Many I have gotten myself but then there have been many that came in collections I got or bought in auctions or at estate sales. Now I don't have the experience with autographs that I do with cards, so my question is over team signed balls, but could also apply to other multi-signed balls.

What percentage of signatures would you say is fair to expect they are legit signatures and not clubhouse signatures or such? I was thinking 2/3 or 70% of the top of my head, but thought I should ask on here. Is there some standard percentage on this?

In most cases, my team balls are not worth paying the exorbitant fee to have it authenticated and then adding it on to the price of the ball. But want to offer the buyer the chance if they wish to get it authenticated but not willing to offer a refund if one or two players were clubhouse or something. Or save the money if they know the signatures well enough themselves.