beauty is only skin deep
Physical attractiveness does not equate to substance or character. Of course that gorgeous model didn't tip you—beauty is only skin deep, after all.
Beauty is only skin-deep.
Prov. A person who looks beautiful may not have a pleasing personality; a person's good looks may not last. Fred: I hope Nancy will go out with me. She's so beautiful! Jane: I hate to disappoint you, but in Nancy's case, beauty is definitely only skin-deep. Don't be so proud of your pretty face. Beauty is only skin-deep.
beauty is only skin deep
External attractiveness has no relation to goodness or essential quality. This maxim was first stated by Sir Thomas Overbury in his poem "A Wife" (1613): "All the carnall beauty of my wife is but skin-deep."
beauty is only skin-ˈdeep
(saying) physical appearance is no guide to a person’s character: My mother always used to say that beauty is only skin-deep. What’s really important is the sort of person you are.