How to distinguish the quality of oil painting?

Commercial paintings are also decorative paintings, the main purpose of which is decoration, and there is no more appreciation value. The main selling points of decorative painting are: 1, technical brushwork, and the author's brushwork is dexterous and superb, and the painting is lifelike. 2, oil painting pigments, with thickness as the selling point, some people like heavy three-dimensional oil painting. Most line drawings are mass-produced. Stick the canvas on the wall, type at the bottom, transition, transition, transition, and finally all the highlights are typed out, and it's OK. Just like being punished by a teacher when I was a child, I did the same thing several times. Well, I studied line drawing for a while, but I was more free in college, just playing. After studying for about a month, you can draw the first line drawing that looks interesting. The selling point above was said by the teacher who taught me to draw line drawings. As for good or bad, I think most of the prices in the store are reasonable. Some works are priced at a high price, so I may not appreciate them. Using different techniques will produce oil paintings with different prices. It should be said that the higher the price, the more the painter thinks about the work. The more you think about it, the more artistic your work will be. You know, many line drawings are copied and then mass-produced. Basic painters can draw like robots without much thinking, which is of course of no artistic value. ) So to some extent, the price can reflect its quality. But for works of the same price, it makes you feel like a good painting.