I tend to stick with sales people who have been good to me in the past. When I shop around for a new car (make and model), that I have never purchased in the past, I give the dealership only one chance to make it right. My wife and I are young looking, and we go and test drive vehicles in jeans and t-shirts. This way, we see if they judge us by our cover.
So far, we have had problems with only one dealership doing this (Mercury). We stood in the lot for 1/2 an hour, and then went inside, and still no one helped us. We turned around, went to another dealer. I wrote the owner of the first dealership about how rudely we were treated, and told him we purchased a Mercury from his biggest rival. We recieved a phone call from the owner himself, appologizing for the way his sales staff treated us. About 2 months ago, on a whim, I went to that same dealership to test drive the Mercury Marauder. Immediately a salesman was there to help me. He took a copy of my liscense, and we drove the Marauder off the showroom floor. It just goes to show, that if you complain to the right people, changes can happen.