I strongly support this and try to practice it in real life. If someone does something bold or that clearly required effort, it’s worth calling out. Bonus if you can do it as you pass them, like going opposite directions in the vestibule of a store, so it’s clear that you’re not looking to get something in return.

For selfish reasons, I also genuinely appreciate people who do something to make themselves stand out. I have trouble with faces, so if you have distinctive jewelry or a big hairstyle or colorful clothing, it makes it easier to recognize you. (Obviously this part only applies in a group social setting and less so in the vestibule of a store.)

One of my favorite instances of this was when I was in the waiting area of a restaurant and saw a guy wearing a loud jacket. I said something like “hey man, awesome jacket!” He got a huge grin, clapped me on the shoulder, and expressed a big thank you. Meanwhile, the person that I assume was his girlfriend smiled and rolled her eyes. I don’t know the background story there, but it was a very satisfying response.

edit: Also, I’ve heard some cool stories in response to this in situations where people weren’t passing by. For example, I might compliment a receptionist’s watch and get back "thanks! I got it from my brother when he went to … " and learn a lot about a person’s history, with the only cost being hopefully making them feel good.

I started doing this after reading a comment on Reddit about how most men rarely get compliments, so each individual one is likely to mean a lot. I don’t limit my compliments to men, but I do try (hopefully successfully) to make sure that nothing I flatter seems predatory. I’ve almost universally gotten positive responses and it’s very rewarding.