There are different kinds of editors. I don't use a content editor at all any more although I did for my first several novels. But then they were editors paid by publishing companies. The last novel I paid two copyeditors originally and then paid a third when I got a few complaints (most erroneous but there were a handful of actual errors).
Whether there are perfect books in existence? Well, that's open to question, but I'm skeptical.
Whether there are perfect books in existence? Well, that's open to question, but I'm skeptical.