Books can be badly-written in any number of ways. The characters may be poorly defined, the plot predictable. The pace may stutter. The author may have O.D.-ed on simile, or rely too heavily on certain phrases ("His scar prickled like fire"). Or the author may assume that his or her readers are total idiots, and load the text with unnecessary clarification. ("'What are YOU doing here?!' she exclaimed, a look of surprise on her face.") A Tragic Overuse of Capitalized Nouns may strangle the reader in Unwarranted Portentousness.
Tyra Banks doesn't really do any of these things. FYI. I mention this in case you, like me, had some kind of suspicion that a person with no apparent experience writing fiction might be, I don't know... TERRIBLE at it. I'm terrible at it, and I write all the damn time.
But she's not good at it, either.