Not as black as he/she/it is painted
Definition 1 of 1
Pro Tip 1/3Metaphoric Meaning
The phrase often depicts the difference between reputation and true nature, similar to judging a book by its cover. 
Despite the rumors about the new teacher, she's not as black as she's painted.
Pro Tip 2/3Positive Revelation
It's used when someone turns out to be better than expected, revealing a positive side. 
The villagers feared the outsider, but he wasn't as black as he was painted.
Pro Tip 3/3Idiomatic Context
Understand it's a set expression, used figuratively, and not related to actual color. 
My brother warned me about his friend, but he isn't as black as he is painted.