I can't think of one, so I pooled the editorial staff. They seem to be obsessed with pedophiles, and they aren't being helpful. Here's what I've decided to glean from the random discussion that seems to have developed.
Tip of the Week: The more unpleasant the main character, the more he/she has to grow during the course of the book.
There's nothing wrong with a character that is unlikable, unreliable, and just plain unpleasant. Even a character the reader doesn't really like can be okay. The thing is, you have to make the character grow. He/she has to learn something or at least make some progress. Now, this is true of all characters, but especially true of the unlikeable ones. And they have to grow gradually throughout the book, not just in a great leap at the end. Basically, you have to give the reader a reason to root for the character, hopefully through their growth.