I worked at a dealership cleanup shop and witnessed several things like this. One time there was a deep scratch on the bumper of a brand new Camry, to hide it the salesman back the car up as close as possible to the wall to keep the customer from walking around the car. Another event that I will never forget, the sales manager and a salesman were passing a football in the showroom and the salesman missed the ball and hit a brand new RAV4 on the hood. They walked over to the parts department and grabbed a bugshield to cover it up. The RAV was sold that day without the huge dent being fixed, only covered up.
I remember having a Ford Harley-Davidson Edition fresh from the body shop and to help blend the areas that were buffed, we had to apply a glaze to the whole truck. There are so many more stories to tell, but to answer your question...dealers use any means to hide defects until the vehicle is off their lot, then it's no longer their responsibility.