'Beautiful', to me, is good will and compassion, pureness and innocence, tolerance, love. I could go on and on.
Someone could be by-the-book beautiful but if they are rude or wretched, I'll think of them as a hag or as just being really fake and "plastic", as it were. I think superficiality is ugly and disgusting, but that's just me...
On the other hand, I think there are opportunities for people who are labelled as "bad" to shine through beautiful moments... Like a convict trying to genuinely make amends for the wrongs (s)he's done.
And then of course, love is a given. Little expressions of affection or care, visible or non-visible. Even things that are done out of the utmost worry of the other person has a tinge of bittersweet beauty to it.
Childrens' innocence and beautiful nature too, of course
(Please look up an episode of Oprah featuring Jacqueline Saburido if you get a chance. If you ever see a safe driving poster with a woman whose whole face is burned, and hair gone, etc, that is her. Before an epiphany after watching this special, I had more of a conventional and societally-normal concept of what beauty was, but watching this changed me. She may have burns over a vast majority of her body, but in that moment she seemed just as beautiful to me as anything could be.)