don't judge a book by its cover

don't judge a book by its cover

Don't base your opinion of something (or someone) on the way it (or one) looks. This report may look dull, but don't judge a book by its cover—I will have you riveted by the facts and figures in no time! I know she's a little frumpy, but don't judge a book by its cover, man!
See also: book, cover, judge

you can't judge a book by its cover

It is unfair to judge the true qualities or characteristics of someone or something just by assessing superficial details alone. He seemed like a bit of a jerk to me, but I guess you can't judge a book by its cover.
See also: book, cover, judge

you can't judge a book by its cover

or

you can't judge a book by the cover

You say you can't judge a book by its cover or you can't judge a book by the cover to mean that you should not judge someone or something by what they look like or what they seem like at first. If he loves her I'm happy for them. You can't judge a book by its cover. We may say that we don't believe in judging a book by the cover, but research has shown that we do, over and over again.
See also: book, cover, judge

don’t judge a ˌbook by its ˈcover

(saying) used to say that you should not form an opinion about somebody/something from their appearance only: When we arrived we found that the hotel we’d booked looked awful, but as they say, you should never judge a book by its cover.
See also: book, cover, judge