When I had my shop it was at least a weekly occurence...Someone has a beat up Barber dime worth $3, they get a coin price guide and look at the Proof 65 column and think it's worth $1000. They think you are crook for telling them reality. How many times on Pawn Stars do the experts tell the people something is fake or worth 1% of what they thought...then they do the interview with the person in the parking lot...always "In my heart" I know it's real, I know it's worth a lot more...they'll be sorry!
That's because of what was told them by a relative who passed the item on to them and they want to believe what their relative told was true and not embellished or not true all together.
I think I've shared this famiy story before. I had a "rich" uncle who also ran a pawn store and supposedly had a safety deposit box full of gold coins. Upon his death and later the death of my Aunt, we were able to see the contents. They turned out to be "California Gold" in 2x2s with 1975ish Red Book pricing. Closer examination showed his Gold was simply the cheap souveer tokens woth about a quarter each. Even Pawn Shop Owners get taken at times.