How can you tell when something or someone is overrated?

Question

Like when someone says "somethings overrated". How do you know something is overrated? Or is it just another way of saying you don't like that, whatever it may be?

Answer 1

It means he's the BEST OF EVERYTHING

Answer 2

We express the terms overrated and underrated based upon our knowledge and sense of the particular action or person.  

Answer 3

When they think they are really good when they're not