Besides, many-many-many AU fanfics in any fandom are, in fact, original works with the characters' names, so it's no surprising that just by changing a few details here and there, your story stands as a true novel. At least two of our very own Roswellians have done this. I remember when I read what RosDreide's story was about, I could clearly see who was Max, who was Michael, and Liz, and how the Antar background was there. But that's because I know it came from Roswell, so I can see the "source" fairly clearly in this "AU" presentation.
If I were to pick the book without previous knowledge I would probably go as far as getting a "Roswell vibe", and go with it


Unfortunately for me, I've also picked books that are as poorly written as the majority of fanfiction out there

You have to consider as well that just because you write fanfiction it doesn't mean you aren't any good, or that your ideas have no value if you rework them a little. If anyone wants to self-publish, you can go to http://www.createspace.com and have it done easy and cheap. No one has to know if you are any good, or if you have an established name on the fanfic world. Of course, if your book is bad, it won't sell too many copies or get good reviews... On the other hand, getting published by a real publisher it's an entire different thing, which we're not discussing here.
But, getting back to the topic, yes, I do believe they have the right to do what they want with their stories, being it delete them, translate them, change them into original works and being snobbish about it. I will probably never pick another story by the author who "burned" me, so it's the author's loss. One less reader for them.