Use your fingertips and palm when evaluating the paint surface of your vehicle. You have many more sensory nerves here than on the back of your hand. Avoid rubbing on a dirty or dusty surface as this will create scratches. Clean the surface first, and then let your fingers and palm tell you the condition of the paint. If you have a lot of contaminants on the surface, you will hear an audible dragging noise from the paint.
This is a companion discussion topic for the original entry at https://www.hagerty.com/articles-videos/Articles/2006/08/24/Fingertips-and-Palm