Each person is beautiful. Like a snowflake, each person is an individual, unique. Beautiful like a mathematical theorem or music. Each person has their own combination of traits that combine to make them unique, special, that tell a story of their history going back to the beginning of time. Physical traits, psychological traits. If a person is unpleasant, there is a cause, a logic to it. Music in a minor key can still be beautiful. All life is a miracle, all life is beautiful like music, art, natural law, or mathematics.
The beauty of each person is a kind of beauty that evokes love. A platonic love, like love of nature, like awe of nature. Love doesn't mean you should be their slave. It means you want the best for them, for them to be happy, for them to get from life what they came here to learn. They can't do that if you solve all their problems.
To see the beauty in each person, you have to stop thinking about yourself. When you see a person, you might think of them in relation to yourself. Are they friendly or not? Pleasant or not? Attractive or not? Good, bad, nice, nasty, better, worse, higher, lower, liked, disliked? All these ways we think of people put them in relation to ourselves. Like monkeys in a cage determining a social hierarchy. It blinds us to the true beauty of each person because the feelings produced by those ways of thinking confuse us, make us defensive.
To see the true beauty of each person, you have to stop thinking of yourself in relation to other people. You have to forget yourself. This is not mystical. Forgive yourself, you don't have to be perfect. You don't have to be the top monkey. When you see a person you might not like, let go of your attitudes and prejudices. Let go of your dislike, anger, fear, or envy. Forget yourself. Accept people as they are. We are all on a path of spiritual development, some are further along, some are less far. Don't think of yourself, understand, sympathize with the difficulties others had to endure which made them what they are. Look for the beauty in their uniqueness, in their variety. Relax. When you are at peace with yourself, you naturally stop thinking about yourself. All those feelings, liking, disliking, fearing, wanting, not wanting that create the dualistic mind set of self vs. other evaporate and you can see the truth, the beauty, the loveliness of each person.