I didn't thoroughly vet this link, but it's a start.
https://centraltendencies.com/2011/03/pawn-stars-is-fake/
If they have legit items brought in then they get as much mileage out of it as they can, I'm sure. But the problem with most of these reality shows is that they don't have time to just hang out and wait for cool **** to happen. They have the crew for a certain amount of time and they need to utilize them. So, if enough organic content doesn't materialize they manufacture content. It ain't like they're going to not make a show because no one brought in any cool stuff this week.
I'll buy that as a definite possibility. But that's quite different than the "it's all fake" comment you had earlier.