I'm with the other commenter above, I have no idea why someone would worry about this. Every gun show, antique fair, estate sale is full of different personalities. If someone comes up to something I'm selling and "schools" me of why I'm priced too high, I smile and let them. Then keep the price where I decided I want it. I'm not influenced by supposed "experts" at places I sell. Neither the low-ballers nor the high graders. If I'm too high, I'll realize it - at the END of the show with no buyers.
Many times in my 58 years I've had someone walk up to me at a gun show when I walk in carrying a VERY common gun and pull the "what cha got there sonny?" Since I was 16 I knew they're trying to scoop something cheap. I let them look, let them give me a price if they want....tell them I'll think about it, and walk away. If you've got a treasure, they just played their hand....and blew it, if the next guy I sell it to gives me MY price. The high-grader shills are more common. Once I picked up a gun, realized it's reblued and priced what a high condition original is worth. I set it back down and someone sidles up and says, "nice gun! you gonna get it?"
Me: no.
He: "looks like a good one, why not?"
Me: "Because it's been reblued, the stock refinished, the rear sight is wrong, and this is broken. It's priced double what a GOOD one costs."
He: "hmm...well...I really don't know too much about those."
Later: I see him behind the same table as the seller - he's his partner, sharing a table. Um....right.
Rule of haggling: Don't trust someone who says something is worth a lot less, or a lot more, than what your experience is telling you.