People judge beauty in relationship to themselves. Another example is in art. If I look at a painting by a famous artist, it is possible that I can't understand it and think it's ugly, but if another person such as a famous painter sees it, he will surely say that it is beautiful. I think people judge beauty just in relationship to themselves. If I wear casual clothes to my job, the people who like wearing formal clothes might say that I look ugly.
Love is blind.
Another example is between persons. If I like a girl and fall in love with her, for me she is beautiful, but for another man she can be unattractive. I remember the end of the movie, Planet of Apes . True beauty opens locked doors. Many people look for external beauty, and they forget about feelings.