There are subjectives, and then there are these. While you may believe a work fits here, and you might be right, people tend to have rather vocal, differing opinions about this subject. Please keep these off of the work's page.
Ignore for a few moments the great Subbing versus Dubbing debate among the anime fandom. There are certain shows or works in that medium that fail on their own merits and prove that being So Bad, It's Horrible is not exclusive to any one side of the Pacific. You know it's bad when even fans looking for a Widget Series exclaim "WTF?!?!?" after viewing. Feel free to curse these titles, anime haters — the fans don't bother defending them, anyway.
Important Note: Merely being offensive in its subject matter is not enough to justify a work as So Bad It's Horrible. Hard as it is to imagine at times, there is a market for all types of deviancy (no matter how small a niche it is). It has to fail to appeal even to that niche to qualify as this.
Second Important Note: An anime isn't horrible just because Bennett The Sage, Professor Otaku, Don East, The Other Side, Doggy D. Dachshund and Conroy Cat or any other Caustic Critic reviewed it. There needs to be independent evidence, such as actual, professional pannings, to list it. (Though once it is listed, they can provide the detailed review(s).)
Examples (more-or-less in alphabetical order):
Art of Fighting had an absolute mess of a 45-minute OVA, with a ridiculous story, depressingly predictable plot twists, and not one interesting or likable character. Heck, the one thing you'd expect it to be able to deliver (spectacular fights) falls flat. And from a video game player's point of view, it has nothing to do with the story of the games beyond the premise of "Yuri gets kidnapped, Ryo and Robert try to save her", none of the signature special moves appear and Ryo has black hair for some reason. About its only saving graces were the decent music and turning Butt Monkey Ryuhaku Todoh into a hilarious nutcase police chief. Watch Bennett the Sage tear it apart here.
Fun fact: The voice for Yuri Sakazaki in this clunker is J-pop singer Ayumi Hamasaki, who made her first (and only) voice acting role.
The Cosmopolitan Prayers, a.k.a. Cosprayers (not "Cosplayers", Cosprayers). The broken English in the title is the least of its problems. The characters are incredibly idiotic, inconsistent, and one-dimensional. The girl who loves the male lead makes out with the main (female) protagonist, and the other girl also likes the guy, and there is no motivation for the Triang Relations. There is random unnecessary Fanservice alongside loads of rape imagery which makes anything potentially titillating just plain creepy. There are no transitions — one minute, everyone's chained up in a cave; the next, they're on a pier fighting with tennis rackets (a power upgrade, by the way). It has a plot that must have been thrown together between rounds and the conflict and characters never give the audience any reason to care. It heavily rips off Power Rangers, only it's much less entertaining. It culminates in an extremely lazy Gainax Ending with singing and rainbows... no, seriously. The whole thing was made by the company M.O.E. (Masters of Entertainment), but they don't show their mastery here.
To add insult to injury, there's two spinoff shows which portray this as bad in the Recursive Canon, to the point where in the second series, it turns out the identity of Cosprayers's writer is kept secret from the public eye.
Dark Cat, an obscure horror OVA from 1991, suffers from many problems such as an unfocused narration, lifeless, uninteresting characters and ugly, practically artless animation. Not to mention the horrific English dub. One of the many direct-to-video OVAs that flooded the market in the late 80s/early 90s, it is best to be left forgotten.
The Yaoi Genre manga Dog Catalogue, with its ridiculous use of 2D characters, a frightfully generic storyline with absolutely no development in the characters and with arguably some of the worst art put to paper◊. Every page is an artist's nightmare.
The Eien no Aselia: Spirit of Eternity Sword OVA adaptation. The game's great; the OVA... not so much. The plot is nothing like that of the game. The pacing is horrible, the animation below average, and the background music is copypasted from the game. The characters have almost no resemblance to their video game counterparts. It's as if the staff made this anime on a lunch break. Thankfully, it's only two episodes long.
Genma Wars, a spinoff of Harmageddon, of all things. There are two major reasons why this series from 2002 failed so very, very hard:
The Gratuitous Rape. Now, to be fair, the series is predicated on one sexual assault: A young woman offers herself up to the Evil King to save her clan from raiders, and conceives half-breed twins. But then, one of the twins is taken to eke out a miserable existence among the Evil King's subjects. After he grows up and leaves the King's castle, he meets a woman and, after being at least somewhat friendly and decent to her, decides to assault her, too. Without so much as a "get away you bastard", she doesn't fight him off. She doesn't even seem to understand the way that she was violated, and pontificates to the effect of, "It felt like his life force was entering me..."
The horrible, horrible animation. It is often recycled, cheap, awful, and so very digital. For example: the "good" Wild Child twin has a wolf for a guide after his mother perishes, and he can talk! The problem? The wolf's jaw literally just flaps up and down. In a better series, it may have been justified, but in this series, it just adds to the seeming laziness of the production crew. His jaw literally hangs open for a few seconds at a time as he "talks", and his English VA has a hokey, Speech Impaired Animal voice to boot.
Honey X Honey Drops, a two-part OVA adaptation of the shoujo manga of the same name. Unlikable and flat characters, underwhelming art and animation, and a very degrading and misogynistic plot that's basically about a teenage girl prostituting herself. Nearly every review on My Anime List is a warning to avoid it.
The anime adaptation of Koi Koi 7 does everything one should not do when adapting from a manga. The animation quality is shockingly bad and the design of the mechs and the characters is blatantly ripped-off from far superior shows (the mechs from Gundam, for example). As if the technical shortcomings aren't bad enough, the plot is compressed to the point of being totally bland and leaving virtually no sign of character development nor meaningful action whatsoever. Above all, it's crystal clear that the seiyuus and the music composer phoned in their performances, as the voice-acting and the soundtrack are bland and utterly terrible to listen to.
The anime adaptation of Mamotte! Lollipop, made by a no-name studio as a cheap cash-in on a mildly popular series. Bland and/or unlikable characters, cheap animation (even for 2006) that's constantly reused, an atrocious English dub that mostly consists of screaming and yelling, and a downright stupidCliché Storm plot with a Gecko Ending even though the manga was already finished long before it came out. Anime News Network states the only people who could possibly like it are little girls who don't know any better. It's one of the very few series Funimation seems to treat as an Old Shame (in fact given their handling of it they likely knew it was terrible when they got it)
The OVA Mars Of Destruction is clearly a sad attempt of being dark and edgy like Neon Genesis Evangelion, only the plot is totally non-existent, and the characters don't really have any development whatsoever and are completely forgettable. The animation and fight scenes aren't any better, either, as if the animators weren't even trying to make an anime. And the title has nothing to do with planetary explosions, which would've been far more interesting.
There's an another Idea Factory anime with the same director, Tenkuu Danzato Skelter Heaven, which is a very similar failure to Mars of Destruction, except the visuals are much better. It's no wonder why Idea Factory stopped producing anime and instead focused on videogames, and Yoshiteru Satou didn't get the rights for directing the Hyperdimension Neptunia anime.
Most anime by Yoshiteru Satou seems to be this. One comment on My Anime List called him as the Ed Wood of anime, and his best anime only got 6/10.
Ninja Resurrection, marketed in the US as a sequel to Ninja Scroll, has horrible no-name voice acting that makes the words "Tokugawa Shogunate" a Brown Note, extremely gross and misogynistic fanservice, and a nonsensical plot about Amakusa with a Devil in Plain SightEvil Chancellor leading to the pointlessly squicky resurrection of Amakusa into Satan where his new evil cronies begin slaughtering townspeople... and on top of all that, the series finally ends there due to people wisely avoiding any further trick-marketing.
Some could argue that the series ended just as it was about to get good (it actually ends as the antagonist groups leap off-screen, implying a big showdown and/or massacre to come). It also features Mataemon Araki, the only likable character by virtue of being a gigantic badass who kills ninjas with combat tentacle entrails. He has barely three lines, but is somehow one of the most fleshed-out and interesting characters.
Pilot Candidate / Candidate For Goddess had Horribly-integratedCGI even for its era, plot holes practically from the start ("Only men can be Goddess pilots... except for this lady"), and an aggressively unlikable protagonist in Zero Enna (imagine an easily-excitable combination of Ash Ketchum, Amuro Ray and Taichi Kamiyanote Joshua Seth (working under a pseudonym for PC) provided the English dub voices of both Zero from Pilot Candidate and Tai from Digimon, but with none of the redeeming qualities of any of them). The greatest failing, however, is that every piece of the story is incomplete. Several characters and concepts are introduced but never explored, each battle is an unfollowable mess with key points missing, and while the focus on cadets should make for an interesting angle, the main characters are barely involved with the plot. And to top it all off, even though the story is too thin and weak to support twelve episodes, it still has a Gecko Ending.
Interestingly, the series was based on a longer manga by the author of D.N.Angel, but the company who animated the series declared itself bankrupt after releasing the last episode as an OVA. It also made the author very hesitant to allow D.N.Angel to get an anime adaptation. Eventually, XEBEC (producer of this series and of Martian Successor Nadesico) made a competent adaptation.
[adult swim] aired this anime once, when the block was still finding its legs. And we do mean once — this is one of very few shows that [as] never showed again after its initial airing. A commercial bumper over five years later said, to paraphrase, "Pilot Candidate: Never Again."
Locomotion, a (now defunct) Latin-American animation channel, dubbed the whole series to Spanish, and in the period before changing hands they repeated this daily since it was one of their few anime left. Not even the (surprisingly good) dub could save this series.
Psychic Wars, a 1990s OVA that suffers from a nonsensical plot, boring characters, flying plot leaps, and bad pacing. It was originally going to be a three episode miniseries, and unsurprisingly, only one episode was made due to its low budget.
Root Search, a 1980s OVA with stiff animation; unlikable, poorly-developed characters; and a pretentious and incoherent plot ripped off from Alien. Here's a review.
The anime adaptation of Togainu no Chi has been panned by fans of the original game for good reason. Admittedly, given the nature of the game and its multi-route system, some elements had to be removed for the censors, but it still doesn't excuse the fact that so many things were removed from the story, people being introduced to the series for the first time didn't know what the hell was going on. Terrible animation (to the point that Episode 12 nearly completely consisted of animation recycling), constant deviation from character styling, and a mediocre script combined to make a fairly celebrated BL game into an animated train wreck. There are even rumours that the anime's director deliberately sabotaged it.
Urotsukidoji: New Saga, a.k.a. The Urotsuki. A dreadful 2002 reboot of the original 1989 hentai OVA Urotsukidoji: Legend of the Overfiend. it has been criticized by many Urotsukidoji fans for having horrible animation (To the point where at episode 3, the animation almost looks like it was done on Photoshop), ugly and poorly detailed art, lousy new characters, terrible CGI that is often overused too much, unexplained plot points, occasional out of sync voice acting, and two very sick and misogynistic gorn scenes. The only saving grace to this train-wreck of a hentai is the pretty impressive soundtrack composed by Masamichi Amano. But apart from that, Urotsukidoji: New Saga should be avoided at all costs.