Impression

As I remember one of the quotes mention that:
" Dont' judge book from covers"
I quiet agree with this point, and I would like to clarify this statement with my understanding:
Don't judge people from first impression...if you do not well the person well, it's better for you to know the person first before you judge them...
even as a police, before he caught some one, he should do some steps (interrogation)
Judgment without know people background =Unreality Judgment