Yes. Believe it or not, there IS a clear-cut worst Harry Potter fanfic of all time, to popular consensus.
It is hilarious, in the unintentional way. Ebony, the main character, is this goth vampire witch who falls in love with Draco and Harry Potter (aka Vampire). Then she has to go back in time and seduce Voldemort (aka Satan). Add bad grammar and spelling to this, and you’ve got a really hilarious fic. Oh, and the amateurish sex descriptions. And the lame puns.
Basically, all the males in Hogwarts are either goth and bisexual and excessively Satanist, or paedophiles interested in watching Ebony naked (mostly the professors, like Snape, Dumbledore, Hagrid and Lupin), or just losers.
It has 44 published chapters, and I actually went to read all. But you might actually decide to stop after five, if you value your brain.
You know, I’ve been trying to write something as retarded as this for a few years, but you just can’t beat someone who writes in a retarded manner and thinks it’s cool and perfectly justified.