Well the gun I'm most likely to buy is always going to be a used wheelgun. And that means I'm going to pick out something particularly cherry, esp. if it "looks bad" in some way (worn finish, screwed up grip corner, whatever) but it's tight and clean inside. I care as much or more about a particular specimen within the general class of critter I'm looking for than I do make/model.
Thus, with the ability to "go someplace else" curtailed if somebody has a tight slick low-milage piece I want, I'll haggle a bit unless the asking price is fair to start with. Pawn shops in particular are "haggle city" - they expect it, and usually price high to start with.
To me, it's about "haggling with honor" if that makes sense...I'd never try and claim a gun is in worse shape than it is (pointing out flaws is kosher though) and if the price is fair, I'll pay it.
(Cherry-picking a good specimen can be an alternative to haggling. My beloved 70's-era Charter Undercover 38 snubbie had uuugly huge aftermarket stocks on and was otherwise undistinguished, but on inspection it was as tightly fitted as any Python. Best $186 I ever spent, and that was the asking price. They didn't look closely enough to see what a gem it was. I once embarassed a guy with a full-size Glock 40S&W at 50yd target work with that puppy.)