In fact, this is a normal psychological reaction. There was a study in which a professor showed them photos of students' daily life that he usually took. Some of these photos were taken directly, and some were slightly modified. After these graduate students made their own choices, they found that more than two-thirds of them would choose the modified photos, thinking that this is what they look like in their daily life. From this experiment, we can easily find that people will deliberately pursue an ideal effect for their own image.
So is looking in the mirror. When we look in the mirror and face ourselves in the mirror, we will unconsciously ignore or dilute some tiny flaws in ourselves, so as to bring ourselves closer to our ideal goals. There are also times when people look in the mirror, and people look 30% better than reality.
People have the motivation to improve themselves in their daily lives, and everyone is different. Some people may be obvious, others may be subtle, but it is hard for one to deny this. And when we look in the mirror, we are very conscious and casual about it!