We might have thought that he would be modest and self-effacing, but this is not what some of the sages said.
According to Rashi, once he gained his appointment as overseer of Potiphar’s house, he became vain and started preening himself and curling his hair. At this point the Almighty said to him, “Your father is mourning for you, and all you can do is to act like a dandy!”
All the emphasis on his looks would get him into trouble, God added, which explains, according to the commentators, how Potiphar’s wife was attracted by him and tried to seduce him.
The temptation to concentrate too much on physical appearance has been with us throughout history.
Looking clean and tidy and making the most of oneself is no problem in itself, but if it controls a person’s life it becomes an obsession and grows out of all proportion.
The Biblical view is that of Proverbs 31, the famous eshet chayil chapter: “Grace is deceitful and beauty is vain, but a woman who fears the Lord, she shall be praised” (Prov. 31:30). The author speaks about women, but the same principle applies to men.
Good looks are nice, but good character is better.