Do you ever see the salesperson again after the sale? I just went straight to the service department.
My sense is that salespeople are primed by people who haven't done any research on what they want and doing all that on the spot at the dealership. They're also not exactly sure what they want and are susceptible to be convinced one way or the other. Even when they like a car, most people tend to be not sure and want to try another car or dealership. Hence the usual deal with pricing it higher, offering free accessories, offering a discount and all that jazz.