Most dealerships do not pay a salesperson commission on the holdback. Most dealerships do not deal on the holdback either, but maybe nowadays they do?
I sold cars for years and I can tell you that I ran across all types of people and some were like my friend Aux. To be honest, I usually didn't sell to people like him. I waited for people who were informed and knew what the numbers were in advance---there is a deal there, maybe a small one, but one that the dealership can actually afford to do. I gave my time to help people and worked with the ones that would carry on a conversation on the premises on a car that we had in stock. The result was that I was salesman of the month more then half the year, year after year, and I built up a clientele.
Most dealerships have their (bad) reputations for a reason, but the ones I worked at had good ones because most of the sales people were customer service oriented, not slimeballs wanting to make a quick buck---funny, but those kinds of guys never swam in the cash and had no repeat/referral business. The car business is like any other sales oriented business: if you want customers to come back or refer other, you have to treat them right.
I would never sell to people who gave such lowball offers that I was wasting my time. I would politely tell them the facts and let them get hammered by a bunch of other dealers, but I would always leave the door open so to speak, so that they would come back to me to actually buy a car. They just "have to do more research."
Davy