Pretty is as pretty does
Pretty is as pretty does.
Prov. It is more important to treat people well than to be good-looking; just because you are good-looking does not mean you are a good person. (Said only of girls and women.) Janice may have a pretty face, but pretty is as pretty does; the way she behaves isn't pretty at all.
Pretty is as pretty does.(old-fashioned)
something that you say which means that you should judge people by the way they behave, not by their appearance 'She's very pretty.' 'Yes, but pretty is as pretty does. I haven't been terribly impressed by her manners.'See a fine kettle of fish, cost a pretty penny