Historically the failing anime are classified at Ani-nouto into several groups, although the borders are somewhat fluid.
Rejects. These are series that I do not plan to touch ever again. The list is populated by both series that I watched and those that were rejected without a chance. Since this update wasn't regular enough, I'll reach to the last announced failure, Yowapeda.
Kyousogiga: Seen none. The DB entry is "Notamina LSD-fueled FLCL knockoff by Toei, poorly". Was in queue since a very old e-mail by Kotaro-Robert Miyahara.
Wake Up Girls: Seen none. With all the attention that one was getting, it probably deserves an entry. DiGiKerot: "cynical"; adds a full review later. Evirus: struggles to acquit. Omo: posts a summary. NovaJinx. It basically comes down to this: do I want to give Yamakan a chance to pollute my resting mind with his filth? I don't think so.
Maji de Watashi Koi ni Shinasai: Seen 0.7. This comes mostly from intriguing pictures in Chizumatic's top rotation and I thought to defy his thick hate laid onto the most interesting character. Alas the chara arrivals were handled so poorly that I dropped it.
Gasaraki: Seen none. Recommendation by HK Guncannon, apparently. Another EVA ripoff? Expired.
Space Dandy: Seen 3 and a couple more. No continuity and mostly total bullshit. From the seen parts, the Laika episode was okay, but overall the good parts do not overpower the bad parts (like in Nichijou).
Tokyo ESP: Evirus says it's a Ga-Rei Zero pre-dux (not sure if metaphorically, but whatever).
One-Outs: Seen 5 at a con. Nasty.
Suzuka: Seen 1. Was announced, actually. Terrible writing and characterization right off the bat.
Mangaka-san to Assistant-san: Seen 0.2. Crude.
Aldnoah.Zero: Seen none. Evirus made it sound intriguing, but everyone is killed, so fails the "Dead Girls" test.
Nisekoi: Seen none. DB entry is "scions of rival Yakuza gangs, pffffft", but mostly dropped because it's open-ended. I know that manga is insanely popular for whatever reason.
Himegoto: Seen unknown. Not much at any rate. DB entry is "them.con junk in 4-minute format".
Rail Wars: All the bloggers say it was dire. All of them.
Girl Friend BETA: Seen 1! Meant to give it a chance, but fortunately it has good in-season competition, so this cute boredom can go die. If you love Sphere, watch Natsuiro Kiseki instead.
Orenchi no Furo Jijou: Seen 1. Not funny.
Inou Battle: Seen none. Blogging exposes it as having thematic concerns and being very pedophillic, so pass.
Nou-Rin: A slice by Jason made it sound perversedly attractive, but Hikago said on IRC that "nou-rin somehow managed to keep getting worse" and "i thought it wouldn't be possible after episode 4", so I have better things to watch.
Arpeggio: SDB wrote "This was excellent story telling from start to finish", although later it became less excellent. I watched literally 10 seconds before I understood that it's not for me. Shipgirls are just too much. And if I wanted 3D, I'd be watching Star Wars: Rebel Something.
Delayed. These are series that failed to keep my interest in the run. They have a chance, if I have a bad gap in available material. It is not unheard for them to get re-instated, although mostly for reason of blogging or other. Latest announcement was GaruPan.
Hanbun no Tsuki ga Noboru Sora: Seen something like 2. Its recommendation stretches all the way back to Lawson in July 2006. I reinstated it as a part of the "terminal disease" run, but eh... It wasn't working for vague reasons. Mostly because the chick was junk. I know how illness or injury damage personality, but I suspect that one was like that from the beginning.
Chuunibyou REN: Seen 8, and it had a start announcement, but oh well.
Log Horizon: Seen 11 - not a bad run! The characters are far superior to its more popular competitor, SAO. But I felt like it was getting into Naruto style drag, so I used the peasant king as an excuse to drop.
Date A Live: Seen 2 and posted a mention. However, it's the same problem as Ai yori Aoshi, where I love the first 2 episodes (and rewatch them often), but the rest is meh. As soon as I figured that Princess was merely the initial hook, I dropped it.
Kotoura-san: Seen 8, posted an opener, but dropped when Kotoura glanced into the mind of a serial killer and broke down (haha spoilers). It was an okay series, but not worth continuing.
Wagaya no Oinari-sama: Seen 1. As pedestrian setup as they come.
Hitsugi no Chaika: Seen 3. Hated the dude for war-liking, ambivalent about the rest, the quest was very dubious, so whatever. The broadcast is still not over and unknown if ends.
Sailor Moon Crystal: Seen 3 (01). I just have one question: was the original this bad too?
Hanayamata: Seen 3: rombic eyes. If you commission an anime to save your flagging business, better make it good. Otherwise you spend a lot of money and it rescues nothing.
Invaders of Rokujouma: Seen 4. Frankly, not excellent as far as "XXX-sou" comedies go. I dropped Sakura-sou even faster, however.
Kinmoza: Seen 1. It was too much (of the fake England mostly).
Tamayura – More Aggressive: Seen 1. If Mushishi weren't the most boring anime ever, this one would be it. Together with GF(K). It's a terrible thing to think, but I suspect Nova was only giving it good marks for the film photography gimmik.
Denki-Gai no Honya-san: Seen 4. Needs a good hate post, but in summary it's like Working/Wagnaria, where everyone is defective. Not even Sensei escapes in the end, I suspect. I knew it was time to quit when they circled back to the G-woman in 04.
Stragglers. There is not such category, but some series linger on the Running list for years. So yeah, ostensibly I'm still watching, but...
Shikabane Hime Aka: Seen 2.5. Evirus tagged it for Fully Awesome, but I dunno... It didn't seem that. Cool fights? Watch J2. I'm not dropping it for easy availability on Funimation's YouTube.
The Third is the obituary for Netflix's DVD delivery business. They refuse to send me the next volume and I refuse to do anything about it. The anime offers a certain middle-of-the-roard action/romance flick from the 90s. Remember Excel Saga? That epoch or maybe a bit later.
Madoka Magica: Seen 1. I know I must watch another episode of it sooner or later, but I find a good excuse every day.
Isshuukan Friends: Seen 0.7. Kinda... too much. Very cute though.
Gundam Build Fighters Try: Seen 3. This is a very, very sad case of merchandaizing gone wrong. The original GBF was great, but this is wholly unnecessary. It's the history that repeats itself twice, this time as a farce.