Advice on taking candid shots of other people?

I love taking photos, especially candids. My problem is – I know how to capture moments, but I find it difficult to take them where the subject is satisfied with how they look in it. I have no problem doing portraits and making the subject look good, but it’s much more difficult in candids.

Moreso, I think they look just fine most of the time… I understand that people become more judgemental of how they look, but to me I embrace flaws and whatnot so it’s harder for me to know. How do I know or do it in a way that the subject will like it?

Thanks!