I learned aesthetics in university. It is a philosophy's part. Our professor cited a clever man who said: the pretty or beautiful is: white, smooth, small, light (not heavy), right? Well then, the ideal is an egg! 🥚
What constitutes an expert when it comes to the faces? You can be an expert who states that Mona Lisa is the best but when most of the modern men do not like her, this aesthetic criterion is becoming useless. There is not expertise when it comes to tastes. If you think a girl is ugly but the experts rate her "ptetty" it's not making her really pretty to you. The aesthetics world is generally freedom of choice. The key is to know what tastes dominate right now and to try to become something like that (for example if you live amongst tribal people who like fat belly, you can afford a beer belly.)