There are bad anime, but this goes a little beyond that. Rather than simply being "objectively bad," these anime were a waste of life, and in some cases, a waste of money. Even my 0.5 star anime are so bad they make interesting conversation. These are the kind of anime that infuriate me when someone even mentions them.
10. Tsukoyumi Moon Phase: The whole reason I watched this anime was FUNimation's brilliant marketing team. Watch this trailer. Now watch the opening. Yeah, so it turns out that the anime is more like the opening. It did teach me a valueable lession. NEVER TRUST FUNIMATION TRAILERS. (What's that? Do your own research? But that'd ruin the surprise!)
9. Gosick: Remember the winter cor of 2011? The one that brought us Puella Magi Madoka Magica and... a bunch of other disappointing anime? Gosick was one that I stuck by for far too long. As you can tell by my dropped list, I'm rather impatient. If an anime isn't good quickly, especially a new anime, I will likely drop it or put it on my perpetual stalled list for all eternity (then later move it to my dropped list when no one is looking). Gosick had such good animation (thanks Bones) that I wanted the story to catch up eventually. Unfortunately, in the 13 episodes I watched, it never did. I got behind, entranced by the spring 2011 cor anime, and never looked back. I've heard that it didn't really end well, so I'm glad I didn't waste another 13 episodes watching it.
8. Pokemon Diamond and Pearl/Advanced: I'm a fan of Pokemon. It was my gateway into anime. It was my gateway into video games. It has a special place in my heart. Needless to say, these series with their mindless filler and terrible characters made me lose faith that the anime could ever return to being close to the glory of season 1. It seems like Best Wishes (a.k.a. Black and White in the US) moved back in the right direction, but a bit of my childhood died while being loyal to one of my favorite Japanese franchises.
7. Hetalia Axis Powers: I'm just glad I don't have a World War II veteran in my family or this anime would be much higher. There really isn't much to say about this anime that hasn't already been said. You either love it or you hate it. I hate it. I find it boring, and I generally hate culture jokes. Next anime.
6. Mawaru Penguindrum: I could never really figure out why I hated this anime so much. (RINGO) A big part of it was the characters (RINGO), but I think the whole style and humor just didn't work for me (RINGO). I found it creepy (in a bad way), disgusting at times (RINGO), and just an overall slow anime that doesn't pay off for what you put into it. RINGO.
5. Shakugan no Shana II: The first season is solid. The second is an awful waste of time. Most of it is filler developing a useless character rather than doing what the first season did best, epic battles and tsundere Shana. I never got around to finishing season III, but from what I have watched, season II could have been summarized in a few OVAs (instead of some of those useless OVAs in Shana S)
4. Eden of the East Movies (both of them): If you're wondering about the poor reviews these movie receive, they deserve them. Talk about dropping the ball. They manage to take an already convoluted plot, make it even more convoluted, make the characters even more boring, suck any likeability out of the fanchise, and then, only then will these movies give you permission to die.
3. Nogizaka Haruka no Himitsu: This anime codifies the mediocre. This anime embraces the cliche. This anime sucked me in somehow for a 12 episode romp of such mediocre clishes, and didn't deviver any payoff. I don't know why I kept watching this anime. Perhaps it's the slice of life lover in me that gave me the false hope that this anime would get better. It pretty much wrecked my faith in slice of life until Clannad After Story came to save the day.
2. Full Metal Alchemist: Sacred Star of Milos: Not much more to say that I haven't said in my review. I PAID MONEY TO SEE THIS!!!
1. Higurashi no Naku Koro Ni Kai: At one point, Higurashi was my favorite anime of all time. And then I watched the first episode of Kai. I won't spoil it for you, but this just ruined everything the first season built (SPOILER).