1. Too many people in a harem...I am fine with a love triangle, but when you have more than two competing over the same person, it gets a little irritating.

2. I'm not a prude by any means, and don't mind smut or even hentai if the storyline with it is good. Most the time this isn't the case - sometimes I keep reading to see if the story is going anywhere...but usually there is no specific plot and the manga plods along to an uneventful or even weird ending.

3. There was a major battle and everything finally came to a head and the main characters win, and then "oh crap" something else happens immediately and we are off on a completely new storyline...no downshift what-so-ever (I have put The World God Only Knows on the back burner for now).

4. You were waiting the whole entire series for the main characters to get together, but it keeps dragging on and on for chapter after chapter...I keep plodding along with it anyways usually, but then the ending just is a bid let down (talking about you Faster Than a Kiss).

5. The main character is a baby or the manga is centered around children age 5 or less...just can't find enjoyment in that. Maybe if I had kids of my own, I would see the cuteness, but then again if I had kids, I probably wouldn't have much time to read manga in the first place...

5. Constantly uses fanservice as a mean to get fans to like this new female character. I don't mind it as long as it doesn't effect the pacing. (For example, Fairy Tail)

4. The bad guy who tormented the main character since they were young and also kills off one of their childhood friends, turns good and is liked by said tormented character. (Again Fairy Tail, I'm sorry but that was just stupid.) Not to mention Erza being my favorite character and Jellal being my most hated character in anime/manga history.

3. Annoying Lolis. (Medaka Box: Shiranui, still reading it but hate that annoying girl)

2. OP Main character with no depth

1. Doesn't update quick enough. As long as the story is still fresh in my head.

5. Too many sidetracks from the main plot.
4. When one of my favorite characters die.
3. Bad art.
2. Bad story line.
1. If it can't catch my interest.

u read BL?

5. No update for months, I forget the plot and drop it. ;o; What was going on in D. Grayman? I don't even remember.

4. Manga has gone on for too long, please give the main character the MacGuffin and end his misery.

3. Uninteresting/Hard to relate to characters. I'm looking at you Mr. Perfect Kirito. D:

2. No movement in plot/boring plot, and it's not an episodic series like Gintama.

1. A good storyline turns incredibly cliche/too mainstream.
For me, Psyren had a great start, but then the "main bad guys" showed up and it became just another battle manga. Same happened to Medaka Box too. And most shojo/harem manga. D: All it does is repeat what every other series does. OTL I ended up dropping most of the top shonen manga out there too because it started getting repetitive - Bleach, Reborn, Fairy Tail, Beelzebub, Blue Exorcist. Shojo romance is even worse. Most of the time I won't even remember shojo manga after I've read them. Only the ones with really distinctive plots or interesting side features stay in my memory - Oresama Teacher, Arisa, Skip Beat and Seiyuu Ka.

1. Too many GUYS!!! RAGH!!!
2. Destroying the moe in moe lolis (like the manga adaption of IS as a good example )(Laura-chan)
3. Bad quality scans
4. Manga isnt good enough to wait for the next chapter to come out
5. bad art, too little chapters, stupid bit*hes, stupid males, etc

1) Lousy art
2) Forced and awkward storyline/dialog
3) Boring
4) The story just sucks
5) Lousy scans

I'll put up with a lot for beautiful art.

Nothing has ever stopped me from reading a manga, with the exception of me getting sidetracked with another manga, anime or game.

I'm sad when a main or side character dies, but you have to pull through it. Don't care about there being too much ecchi, I mean it's usually their as comic relief rather than something to move the plot on.

Anyway, I never go off an anime for stupid reasons like a character dying, too much ecchi (is that possible) or even clichéd story. Only boredom is the main determaining factor in whether it keeps my attention.

lol i agree with ll your reasons especially the hitting part... chick be crazy

I try my hardest to make it at least through the first volume of a book but, its not always easy.

1.) I absolutely HATE it when the main character or one of the important characters is the most wishy washy, useless female to ever be created. And its not just Inoue from bleach, she can be kind of a slight improvement from the crap I've blocked out of my mind. Whenever the story has a hint of "i know I'm weak and useless but I can't leave you alone so I, without any combat training or specialized knowledge in what ever needs to be done will follow you (most likely Blindly) into a very dangerous situation. Which I know you can handle alone, but I want to be near you, so you will get unnecessary injuries trying to protect little old me" B!t@H!!!! Stat Back! Grrr!!! To be clear, This scenario is acceptable " I have no combat training, but i have specialized knowledge that is needed, I am a wimp but even wimpy me can't let him go into an unknown situation. I need to woman up and help, but scared. Will go anyway" This last scenario can lead to more character development because it effects all character. But The first example GRRR!!!!!!!!!!!!!!!!!. I'm done.
2.) Wolf Guy... Need I say more? I'm so hurt. I want the time I spent reading to the end back. I want it back so bad. I never been deceived so hard before. For those who don't know, this is an example of a plot going from "This is soo totally freaking AWESOME!!!" to " WTF!! Are you serious, wait...WHAT!! Da Hell!!
3.) Very predictable story with nothing new. A lot of stories are predictable, but they can bring their own flare. But just as many refuse to be innovative. I'm looking at you shoujo genre. Like seriously. Yaoi and Shonen are leaps and bounds ahead of shoujo in variety when it comes to plot, character development, everything IMO.
4.) Too Much fan service. I'm between a rock and a hard place. Since I tend to read more shonen, than seinen or any other genre, I'm constantly running into panty shots, suggestive poses, and suggested incest usually initiated by the sister.(sigh) This is usually where I again curse shoujo for being so mediocre and curse myself for not knowing enough seinen titles to run to. Then I curse the author for having a good plot that keeps me reading until the fan service wins and i drop the manga all together.

Ok, I'm done ranting
All these can be applied to how I watch anime as well.