I trawl regularly for any fic--bad or otherwise--for GoF, but I honestly think I'm the only person who's written fan stuff for that book. I won't say it's an obscure book, but it doesn't seem to attract any of the demographics that typically write fanfic, and it doesn't get taught in schools. (All those guts and terror-piss would probably put some folks off, anyway.)

Steven Pressfield's mentioned that a movie project may be in the works, though, and I'm frankly terrified of what'll happen if/when that comes to theatres.

As most people are pointing out, badfic tends to occur more often in commonly-read continua, which includes some things you wouldn't necessarily think of (using the ones Emmtheory suggested as examples):

Iliad trollfic (NSFW): "Forbidden Love:: The Iliad"
Iliad/ENRON crossover (except not really? that's what it claims to be, but I don't think the author knows what the Iliad is): "The Legend of Enronia"

Epic of Gilgamesh/BioShock crossover trollfic: "Gilgamesh: Challenge of the Soul" (by "Sue Mary")
Epic of Gilgamesh I-don't-really-know-what-to-make-of-this: "The Scribe of Gilgamesh"

a modern retelling of Oedipus the King: "The Boss's Little Problem"
Oedipus with mpreg: Oedipus: The MPREG Edition"

I didn't find any "Leaf by Niggle" fic, good or bad, in the Pit. As others are saying, in terms of books, if it's widely read; widely taught in schools, as Homer, Sophocles, and Gilgamesh are; or otherwise has cultural currency; there's more likely to be badfic. If it's denser, more difficult to imitate, less open to shipping, or more difficult to understand, it's less likely to get badfic — see Lovecraft, Borges, House of Leaves, et al.

*xkcd, Saturday Morning Breakfast Cereal, and other webcomics with no or minimal story arcs.
*Most short poetry, again due to the minimal narrative.
*The Feynman Lectures and similar nonfiction, because...it's nonfiction.
*P.G. Wodehouse's stories, because I doubt most badfic writers would have even heard of Jeeves and Wooster.

That said, the Ironic Overpower is probably already conspiring to create xkcd badfic.

The Games, because not many people remember that series and there really isn't much you can work with, fic-wise. Unless it's ship-fics, there's always material for ship-fics.

There was a time when I'd be surprised to find a Lovecraft badfic, but now Cthulhu is moving into popular culture (I'm looking at YOU South Park) meaning that, while I haven't looked, I'm sure that it's out there now with people ignoring the rest of the Pantheon of Elder Gods and sanity-shattering aspects and just seeing the tentacles.

Also Wheel of Time seems likely as I doubt many people get beyond The Dragon Reborn (Book 3). This leaves a lot of questions unanswered in the mind of the reader, and a lot of things unclear, so if a WoT badfic exists, I imagine it'd truly be terrible.

You'd have to be quite the fanbrat (or any type of fan of Joyce, for that matter) to so much as read Finnegan's Wake.

Same goes for House of Leaves. That book could quite possibly be able to fry the brain of an average fanbrat in nothing flat.

• J.L. Borges: his writings are so complicated that no fanbrat would ever understand him, so it's less likely to get badfic.
  - Same applies to J. Cortázar.
  - And to Latin American writers in general.
  - Crime and Punishment, maybe?
  PS: I had thought of War and Peace but I was proved wrong.

Hmm. I thought of a couple and then looked them up on FF.net. Results?

-Pellinor series -- sadly does have some badfic. And I'm the only person I know who has read those!
-One Flew Over The Cuckoo's Nest -- ... At least two badfics or bordering on badfics. Out of /seven/ total. I barely read some of this one before I felt like gagging.
-Atlas Shrugged -- Huge book size should discourage it, right? Apparently so, but then again I don't see any fics for it. I'm not surprised about that one.
-I expect that more obscure plays that people only read in English class would be pretty clear also. The Piano Lesson, anyone? ;]
-I'm also going to state the obvious with poetry. Seriously, how can you even write fanfiction (or bad poetry) based off of even a poet, nevertheless one poem? (I do hope the Ironic Overpower doesn't prove me wrong there.)

Almost anything that doesn't see popular traffic will get less badfic than anything that does see traffic. Anything that requires effort will get less, too.

This is because anything that doesn't get traffic also gets less fic in general, and because 90 percent of anything falls short of superb quality, that 90 percent of mediocrity (and perhaps within that, the 5 percent of truly horrid badfic) is going to be smaller.

Goodfic expends effort, so may happen more often to obscure canons, I think. Goodfic authors may jump to another fandom suddenly and write good fic there because they have the patience and the will to expend effort to do so???

Maybe???

Cal Leandros
Gold Digger
Cthulhu Mythos
The Filmation Ghostbusters (the first cartoon, not the ones based on the movies)
the Pendragon Series
Jonah Hex

Those are the few that come to mind, but I'm sure that there are more. Hm...It's only a matter of time, I suppose

...go to the Musée des Univers Perdus. That's a library of every lost work ever written in World 1 or a Word World.

Three threads in a row is a bit much, especially when two of them're posted within hours of each other.

I would expect very little if any Iliad or Epic of Gilgamesh badics. No badfics of the plays of Greece either. I'm having a hard time imagining a Leaf by Niggle badfic too. The list goes on and on.