Dealers who tell customers: "We can't get you financed unless you buy that $1,500 extended warranty." Or GAP or etch or whatever.
Dealers who tell customers: "You don't qualify for credit, but we can get you financed if your wife (or husband) signs with you."
Dealers who tell customers: "Oh, that's our Internet price for the car. It's for good credit customers. Your credit's lousy, so you'll need to pay more for the car."