I have to say that I never understood the claim that Knox was being persecuted because she was so attractive. She isn't, and even if she was, that's something that usually helps a case rather than the other way around. Actually, that part can be explained. People make false confessions for all sorts of reasons, and might know details that "only the killer would" because police interrogators provide them, inadvertently or on purpose (see here, here and here, for example). That's why it's important to 1. record interrogations in full and 2. have forensic evidence that supports confessions. I don't know about the rest of it, though, and certainly implicating an innocent man does not reflect well on her. Sometimes false confessions also involve accusations against other parties (e.g. Jessie Misskelley of the West Memphis Three), but in her case she simply fingered him as the sole perpetrator, didn't she?