No ALLCAPS, no bold, and no italics unless it's the title of a work. We are not yelling the DMoSs out loud.
Crazyrabbits: DC Comics' The Rise of Arsenal #3: In what is probably one of the worst cases of character assassination in recent memory, Roy Harper (Green Arrow's former sidekick) goes spiraling downward after the events of the already-hated Cry For Justice (where his arm is lopped off and his daughter killed during an attack on Star City by Prometheus). Trying to cope with his loss, Harper beats up his daughter's supervillain mother (and monologues that it's alright to beat her because "she liked it rough") and attempts to have hate sex with her after he ties her up - which then leads to discovery that Roy is impotent. He then gets hooked on heroin (again) and imagines that a dead cat he found on the street is his daughter. The comic then turns into full-blown Narm when Batman shows up and proceeds to kick the living crap out of Harper while saying, "I'm your friend." Everything after this is practically a relief from the horrible lows portrayed in this issue.
Sick Brit Kid: This troper was pissed enough by the entirety of Cry for Justice, but the moment that murdered comics forever for this troper was the death of Lian Harper. Much like Linkara, one of this troper's favorite comic series is the Titans. Lian's presence helped humanize her father, Arsenal, as well as provide a likeable character that had good potential to develop into a good character down the line, herself, much like Roy and Dick Grayson. Her death in Cry For Justice just reeked of Joe Quesada-esque "lets make Roy cool again by getting rid of the stuff that makes him look old" style of writing, removing one of the more interesting dynamics of Roy Harper's character: Being a single father struggling between his life as a superhero as well as being there for his young daughter. There was even a parallel in the fact that after losing Lian, Roy falls back into his old heroin habit before getting his ass kicked by Dick and then proceeding to become a cliche Nineties Anti-Hero, essentially a Darker and Edgier form of how Peter Parker became a womanizing grown man living in his aunt's basement having multiple one-night-stands after One More Day.
Jonn: I'm not sure which of the many Take Thats in The Authority was the DMS for me, but I managed to narrow it down to two candidates. One was when the team does a little... international intervention, after which when Hawksmoor blows off President Bill Clinton's concerns about reprisals against the United States of America. His response is that the team isn't actually American, and the bad guys would just have to come after them. Because we all know how logical terrorist groups tend to be about such things. Also note that the team is question is mostly American. In fact, it's slightly lower, proportionately, than the usual lineup of the Justice League of America, which the remark was a Take That at (Wonder Woman: Greek. Aquaman: Atlantean. Martian Manhunter: Martian. Superman is Kryptonian, though he's basically a naturalized American.) And behind him in the camera pickup at the time is a bunch of people wandering in and out of the party they happen to be having at the time, offscreen, in various states of dress and sobriety.
Little Red Hen: The Green Lantern story arc, Emerald Twilight, in which the higher ups at DC & the Green Lantern editors outright tried to assassinate one of their oldest characters, Hal Jordan by making him evil to shock readers after the end of the status quo shakeups of "Death of Superman" and "Knightfall". And it wasn't that they just tried to get rid of Hal, but also all the Green Lantern Corps for one new guy. The true moment of suck, however, comes when reading the editor's columns in those #50, where they outright admitted they were doing it all because they thought Hal Jordan was "boring" and "it was too hard to tell stories about him". Give Geoff Johns some credit, he managed to prove that those editors & writers were just lazy.
Regu: The more and more this troper thinks about it, the death of The Human Bomb in Infinite Crisis becomes one. It was absolutely cruel, as Bizarro just kept bashing his head in. It gets even worse when you consider that he's an old man, being murdered by someone who is essentially a child. Other than that, it was an unsatisfying end to a great man and a great character.
Katsuhagi: Identity Crisis was a mess all around, and the dethroning moment for me wasn't even the one people cite most, the rape of Sue Dibny, but a more subtle one. Mainly, the sight of Sue's charred corpse being held by her weeping husband and the revelation that she'd just discovered she was pregnant. That did it for me, since the story went from dramatic to Trying Too Hard right then, by throwing the fact that she was pregnant onto it it was essentially screaming "Oh, you see this tragedy? Well it's tragic! Now have some more!" It was just too much. Not to mention that it causes a huge moment of Fridge Logic when you know that the Gingold Ralph got his powers from also made him sterile, so who exactly was the father of Sue's baby?
Dr Zulu 2010: Speaking of Identity Crisis I have to mention Firestorm's death for many reasons. 1. He barely appeared in the comic, so it comes as super cheap. 2. He dies pierced by a sword and has to flee before he explodes because "this is what happens when a nuclear reactor is punctured." No, this is what truly happened when a nuclear reactor is punctured. And even if we have to believe it, that would not happened in Firestorm's case because he is not a nuclear reactor. He has nuclear-related powers and he is not corporeal. And 3. It's just another one of DC's trademark cheap deaths for the sake of it and because they need to introduce a new character, only to bring him back later making the thing pointless in the end.
Tropers/Darkwing: Oh and let us not forget their attempt to make Deathstroke seem badass by beating up the Justice Leauge. Flash manages to impale himself on a sword. Flash has super reflexes and perception. But even worse is Green Lantern. Most powerful weapon in the universe. He decides to try punching Deathstroke and getting his fingers broken. This was Kyle Rayner, the guy who always made different constructs because he had so much imagination, and he didn't even put a suit of armor on first? If you want to make a villain look dangerous, don't have the heroes act like total idiots. That just makes everyone look bad.
Tropers/Gojirob: Add to that, Wally West has been fighting Deathstroke since he was a kid, and certainly the other Titans would have clued him in on facing him. Wally, just based on casual chat with Dick Grayson, would know almost as well as Batman how not to face Deathstroke.
What about Zatanna Mind wiping Doctor Light making him the goofball we know. Then mind wiping Batman based on his objection of the first mindwipe? This was made after the New Teen Titans, where among most things, Zatanna pretty much called Raven out for doing a similar thing to Kid Flash, which promptly turned the team against her prior to Trigon's first arrival.
Time Traveler Jessica: the last page of the New 52's Catwoman #1 has proven to be very controversial, and not just because it depicts Batman and Catwoman going at it in a scene that would look more at home in Tarot: Witch of the Black Rose, but because in the process of undoing Selina knowing Bruce's identity they now have the two of them engaging in semi-anonymous sex with each other without even bothering to take off most their costumes, throwing out years of UST and Character Development. This is a perfect example of giving fans exactly what they wanted, and yet judging by the reactions of many Bruce/Selina shippers, no one wanted it like this. Not to mention Bruce's consent is pretty nebulous.
aldo512: In Red Hood and the Outlaws, the reveal of Crux's motivation was unbelievably stupid. For those who don't know, his motivation is, when he was young, a Tamaranian ship crashed and killed his parents, leading him towards his hatred of aliens and Tamaranians in general. That's it. His entire motivation, his reason for believing all aliens are evil, is because ONE alien had an accident while flying and his family just happened to be there. This is the equivalent of seeing your family die in a plane crash and deciding to kill every pilot in the world as revenge. The worst part? This is presented completely straight. Crux's motivations are never called into question, he never considers the idea that it could have been an accident, hell, the very next issue has the gall to refer to it as a murder when it's not. If it's anything, it would be considered manslaughter, unless the war ship somehow lacked the weapons to kill two humans without crashing.
kensu: In Promethea it happens during the (first) journey through the Major Arcana of the tarot, when they get to the Star card. This is when it becomes obvious that Alan Moore isn't just spewing new-agey mystical nonsense, but actually believes what he's saying. This is when it goes from being a comic book to a religious tract, and it rapidly becomes unreadable.
Asger: To be honest I wish I could count the entire New52 idea thing DC's doing as a dethroning moment of suck, but if I had to be specific I'd say the idea of hooking up Superman and Wonder Woman is the ultimate low-point. I mean seriously, the characters of Clark Kent and Diana Prince are so far apart from each other in terms of personality it's not even funny, a relationship between the two would barely last a month. Clark is a nice guy farm boy, and Diana is a warrior princess. Yet here they are, being touted as the new power couple to grab attention. In elseworlds stories the thing that annoys me most it's when the writers throw Lois Lane off a bridge just for this stupid pairing, and now the morons at DC just went and made it canon. Nice going DC, keep on grabbing plot ideas from 15 year old girls.
LLSmoothJ: Wally West finally makes his New 52 debut. Quite possibly the most anticipated (let alone requested) debut in DC since it started. What we got is basically a black kid who already has a criminal record (and yes, I said kid, as he's no longer a young adult like Dick Grayson) with neither of his parents anywhere in sight. So not only has Wally been retconned out of his own generation, but now he's more or less a stereotypical black kid who grew up in the 'hood! Unfortunate Implications doesn't even begin to describe this. I'm really hoping that the New52 is going to have their own Crisis and soon. The sooner we can get rid of this walking stereotype and get the real Wally West back, the better.
Doctor Sleep: The ending to Death of the Family ruined Batman for me. What should have been a definitive and memorable story arc about the Joker turns out to be just another Killing Joke imitation. No major changes, no reveals. Just DC doing business.
The Joker was taken out of the spotlight for a whole year under the implication that he'd been concocting his most devious act of villainy yet, but in the end the whole thing falls flat. The Joker was bragging about how he knew the Bat-Family's secret identities and managed to prove it by killing people they knew outside of their masks. Then we find out that this was all a lie and the killings were mere coincidence.
Batman then pulls the exact same move by threatening to tell the Joker that he knows his real name, yet this is later revealed to be a bluff as the Joker's profile on the Bat-computer has "Name Unknown" on it. What's more, Batman reveals that at some point he actually talked to the Joker as Bruce Wayne. Did it not occur to him that there might be consequences? This is all just to show us that in the end the Joker doesn't really care who Batman really is, contradicting a plot that's been spanning 6 whole months and several titles.
And now the New Gods have been ruined. Making human characters darker and edgier may make them more interesting, but when you do it to paragons it just reeks of market research. What made Darkseid stand out in the original 4th World series was that everything around him was so much lighter and softer. When you take away the lightness, Darkseid doesn't seem like such a big deal.
k9feline5: I was a fan of DC Comics for about 20 years, from 1985-2005. My all-time favorite series was Justice League International, and my favorite character from that series was Blue Beetle (Ted Kord) (many of you can now probably guess where I'm going here with this). The issue that made me quit DC altogether was Countdown To Infinite Crisis. There's nothing about this worthless, poorly written piece of crap that I don't despise. There's the superheroes who don't try very hard to investigate the theft of 100 pounds of kryptonite because a lowly "second stringer" called it in, the snotty, dismissive attitude of most of these "heroes" towards Ted, the fact that the only heroes who treat Ted with any modicum of respect barely knew him while the ones he had a history with are the snottiest of the bunch, the way Ted gives internal monologues about how "awesome" these heroes are at the same time they're treating him like crap making Ted look like a masochist so even Ted doesn't look good here (no, Linkara, this isn't even faintly the "greatest Ted Kord story ever told"), his pointless death, the fact he's getting killed by his old JLI friend Maxwell Lord (not that you could tell they were ever friends from this issue), and the way Max reveals he's been Evil All Along, which contradicts words, deeds, and even thoughts recorded of Max in those JLI issues. But there's one moment that's worse than all of this, that's a D Mo S for me not only for this issue, but for the entire DCU, a moment so bad it made me say Screw This, I'm Outta Here! on a hobby I'd had for 20 years. It's where Max "reveals" that as part of his Evil Plan he'd been "Keeping the League ineffectual for years". The only League Max (and Ted) had ever been a regular part of was the JLI so either: 1) this was a very deliberate, intentional, mean-spirited Take That on the part of the writers at the JLI, or 2) the writers were idiots, too stupid to realize that's precisely what it came across as. This moment was so bad that it became the one part of this one-shot that DC has tried to correct, by instead saying that Max had more of a gradual Face-Heel Turn, but that still leaves a DCU without Ted, murdered by a friend it should have been completely OOC to murder him, so that every story since then involving JLI survivors will be about how evil Max was, and now the entire JLI history along with a lot of other good things has now been retconned out of existence by Flashpoint, so, no, I don't regret my decision to quit DC.