3rd party or official supplements, this thread is dedicated to the nonsensical, the offensive, and the just plain bad products in the tabletop industry. My Gaming Horror Stories gave us opportunities to "hate the player, not the game." This thread is all about hating the game! Or at least certain aspects of the game. Share your thoughts and horror stories about sourcebooks not fit for print!
WG7 Castle Greyhawk: The iconic dungeon of Gygax's campaign setting, the true depths of this castle remained unpublished to this very day. After Gygax parted ways with TSR on bad terms, some genius thought to make a module-long April Fool's Joke of an adventure.
Castle Greyhawk was advertised as a serious supplement, but it was full of NPCs and locations taken from modern pop culture, like Doctor Who and Scooby Doo. Greyhawk fans and Gygax supporters were enraged. The module was a slap in the face and just smacked on mean-spiritedness on the part of TSR. There is always the possibility that the creators of the module had little ill intent and didn't realize the potential negative fallout they were about to unleash.
World of Darkness: Gypsies: Who thought that it would be a good idea to give a real-world ethnic group stereotypical magical abilities and power levels based on "bloodline purity?" White Wolf fans would like to forget that this book even exists.
War!: Shadowrun sourcebook which is badly edited and derided as being against the spirit of the setting. One particularly notorious adventure plot involved the PCs venturing into Auschwitz to loot the place for valuables while ghosts of Holocaust victims attacked them. Very poor taste.
Black Tokyo d20: Modern horror setting which incorporates hentai tropes. Very juvenile rules: steal a woman's panties, gain mind control power over her if you sully the underwear with your bodily fluids. Spells that are only activated by incest? Yuck!!
World's Largest Dungeon: "Don't play Druids, they'll be useless in this adventure!" It's exactly what it says on the tin: one big, long dungeon crawl. You get a lot of loot, but you can't sell it because there's no towns or vendors in this dungeon. Just one encounter after another. There is a plot going on, but I don't know if it's any good.
Encyclopedia of Demons & Devil, Volumes 1 & 2: CR 20 monster with only 40 hit points and little in the way of dodge buffs? How about a CR 5 creature with a DC 30 Save or Die effect? Or a devil with giant scissors that goes around and performs abortions on peasant women? Or a new "evil pacifist" core class that's just a Cleric knock-off? "Best publisher in the industry" my ass!!