you can'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
References in periodicals archive ?
As the saying goes, you can't judge a book by its cover.
The old saying is true: sometimes, you can't judge a book by its cover.
COOL DWELLINGS: Encino might not appreciate being called ``ordinary'' on the cover of the first anniversary issue of Dwell, but the Valley house featured inside demonstrates that you can't judge a book by its cover.
If there's any lesson the Barbis would have you learn, it's that you can't judge a book by its cover.
The myth that consumer debt is evil is as suspect as the bromide that you can't judge a book by its cover.
Idioms browser ?
Full browser ?