I agree with a lot of the above, especially the idea that "too far" can occur when it's your own baggage. For example, I have cerebral palsy, but it's very mild. Show me a book or movie starring a "stereotypical" person with a disability (childish, scares easily, has to be coaxed to do basic things, etc), and I will throw the book down or change the channel. As for other cases, I think flaws only go too far when: (1) they're too graphic (the Nazi who delights in describing every detail of the rape of the Jewish woman). Or, when the flawed protagonist experiences no redemption or change (the gambler who stays mired in addiction and selfishness for the whole book, the woman with PTSD who never faces her fear).