Pawn Stars is a show where people come in to trade things like priceless family heirlooms for a coupe hundred bucks.
Basically throughout the course of the show, about 5-10 people bring in junk that they think is worth a lot, only to learn that pawn shops are actually places where you get paid abysmal amounts of money so that the store can make enormous profits.
Pawn store professionals note that Pawn Stars is an unrealistic representation of how a pawn shop actually works. For example, most pawn shops don't call in experts to price items, they make a guess. While this is true, pawn shops everywhere are basically admitting that at least one party in the sale will be getting ripped off. The only difference between that and Pawn Stars however, is that in Pawn Stars, everyone knows the seller is being ripped off.
Another reason disgruntled pawn shop owners point out is the lack of stolen goods and the high amount of actually interesting items that come into the store. Personally, we think they're just mad that they didn't think of this idea first.