Whether the touch-up technology is good or not mainly depends on light reflection and color difference: whether to paint or not can be judged by comparing the light and shade of the reflected light from the car body. Generally speaking, the reflected light at the paint spraying place is very dark. For metallic paint, you can check the metal content on the paint surface. Feel the smoothness with your hands: the place where you paint is not smooth, and you can also feel the unevenness of the car body. Observe whether there are polishing marks: as long as the putty is polished after scraping, there will be traces and many thick or thin stripes. Knocking on the car body: the sound of the sheet metal part is low, and the thickness of putty is different from that of the original car paint. Observe edges, decorative strips and rubber seals: look for traces of residual paint and "flowing paint". Open the cover: check whether there is any residual paint and the color difference with the body paint. These are all taught me by the master of Baianbang. All the cars in our unit are maintained there. The master is very nice and professional. Hehe, please choose the best answer that helps you.