cat behaviour

I always hear all sorts of people say: "my cat is crazy!" or "my cat is unbearable, he spites me on purpose!” and so I listen carefully to the description of the misdeeds of the cat in question expecting to hear something really problematic. Yet, most of the time, it's nothing like that: at the end of the conversation I know the cat has no problems, while his human really needs help to understand what it means to be a cat.