This is a bias that psychologists have studied. For decades psychologists have studied what is known as the what-is-beautiful-is-good effect. In these studies we observe that beautiful people are consistently rated as more intelligent, more able and more virtuous than the less attractive.
Think about that. The beautiful aren't simply judged as smarter and more talented, they are also judged as being better human beings. And because of this the beautiful gain a variety of social advantages. For example, the beautiful are more likely to get hired or get the promotion. Let alone the advantages in social popularity and interpersonal attraction.
I bring all this up as I was visiting with a homeless man the other day and he was missing a lot of teeth. That isn't uncommon where I'm spending more of my time as poor and homeless people without access to basic dental care will simply lose their teeth. Which can make them look sinister and scary. It's an automatic aesthetic judgment of ugliness that can affect your heart and mind. When looking at toothless smiles you need to beware of the what-is-beautiful-is-good effect (or, rather, its inverse: what-is-ugly-is-bad). And you need to educate your children about this as well. Because their knee-jerk reactions will also conflate the aesthetical (what is ugly) with the moral (was is bad).
Because as we talked about in my class those many years ago, the aesthetics of the gospel finds beauty in unlikely places. The gospel reverses the aesthetic standards of the world as the "ugly" becomes beautiful in the eyes of heaven.