There is something kind of attractive and weird about perfect teeth. Nowadays some people have such perfect teeth, after they get Invisalign and bleach them. When I see these perfect teeth, I cannot stop staring at them, and that is sometimes embarrassing. To not feel uncomfortable, for myself and the owner of the perfect teeth, I just tell the directly “You know, you have such perfect teeth. I like them. Did you get some sort of treatment for them?”
The habit of staring at people when I talk to them is also awkward, I just don’t notice it. I am actually curious to what extend others notice it – I wish someone just told me. But that requires such level of directness that most people are incapable of.