Payment info needed before price negotiation?

I spent the majority of my adult life practically living in vehicle showrooms of various kinds all over the country. Unfortunately, I never actually got to see some of the tactics related as "Old Wives Tales" on this and many other forums.

Any salesman in today's world who honestly would attempt to commandeer a credit card or a set of trade-in keys in order to keep a customer against his will, better look a lot like Hulk Hogan. He is bound to get a beat-down or worse in his first week.