"what you see is what you get" or "never judge a book by its cover"

In the world we live today, there are a lot of social media in which we publish pictures and makes profiles and everything revolves around our physical appearance. This is why people use to say "what you see is what you get", because today is something so normal to judge someone across a picture.  However "never judge a book by its cover", is a phrase that also is often heard from the people, so which is correctly? I inclined more for "never judge a book by its cover".

First let’s define both of the phrases.

"Never judge a book by its cover": outward appearances don't reflect what is inside the person.

"What you see is what you get": what you look like is what you are.

I still believe that people is deeper than only him or her appearance, there is no connection on what you are and what you wear, even more: what exactly means what you look is what you are? What my jeans can tell to another person what kind of things I like, what I am a good at, etc. is something so stupid by my point of view.

That is what I believe that you cannot judge a person because the way he or she looks, is so usual that people get surprises (good or bad) because they do not give the chance to new people.

There is one thing, I can agree with “what you see is what you get" and there is when people is unclean, when they smell bad, have dirty the hair and things like that, there is always the option that he or she results to be a great person, but something have to be wrong with them if they do not care of their personal cleanliness.

I think today is so difficult to leave aside the prejudices, because we have access to everyone profiles because of the internet and info of other people, but we don’t really know them, but I still believe that people should not just keep what he look outside and give the chance to know the others.