The Crew of the Copper-Colored Cupids: Towards the beginning of the short story "The Resurrection of the Wellsians", Edwin has some trouble fastening the hatch of the Fog Ship and eventually runs along to follow the others, leaving it open. This allows the Wellsians to steal it and obtain interdimensional travel, also seemingly stranding the rest of the cast on Venus, though that they quickly find a way around.
In Pay Me, Bug!, the protagonist has some security forces pinned in a stairwell; that is, until he mentions that he only has one pistol in a voice loud enough for them to hear him.
Uber-mage Fey has stopped the Necromancer three times and defeated the supervillainess Hekate. Only just recently have we learned that every one of these battles has caused Fey to draw enough life energy from ley lines that she has caused ecological disasters each time. Oops.
During the Birthday Brawl, Bladedancer gets word from the Tao that the hostage situation to which she and Generator have been called will resolve itself without anyone getting hurt as long as nobody tries to go inside and intervene. Bladedancer and Generator are perfectly happy to just sit around and wait, but one of the local superheroes, a moron who doesn't respond to the police trying to flag him down, decides to charge right in and everything goes to hell.
Serina: The sea stewards (thalassic gravediggers, nova daydreamers, and greenskeepers), managed to turn the oceans of their titular home moon into a peaceful and bountiful paradise. However, while their efforts slowed down the global cooling that would bring about the end of life on Serina, they also made the entire marine ecosystem extremely fragile and utterly dependent on them. Once they disappear from the moon, which coincides with the proliferation of greenhouse gases, the entire ocean biosphere collapses, leaving only a handful of surviving organisms.
The site has a Rule of Cautious Editing Judgement meant to prevent any Flame Wars in This Very Wiki (read that page for more). Unfortunately in some situations, some tropers completely ignore this rule, leading to the mods locking the page most likely for good... which means nobody gets to add and edit future tropes.
In extreme cases, there's the Permanent Red Link Club, in which the tropes are so misused, become a magnet for racial slurs and personal attacks, and the like that not only the page is locked, the page (and in some occasions, the entire trope) gets deleted, never to be used again. Forever.
And in less extreme but still unfortunate cases, Real Life examples can be cut and prohibited from a page if things get controversial enough. On that note, there's also the Example Sectionectomy, which examples are either cut entirely or relegated to a separate area such as Darth Wiki or the Discussion tab if things get nasty. And if the examples had previously been divided into multiple pages, then the deleted Real Life examples won't even appear in the page history for you to browse.
This is the reason why Fetish Fuel and Troper Tales no longer exist. Some people couldn’t resist putting controversial and creepy content in Fetish Fuel and Troper Tales, which lead to these sections being sent off to separate off-site wikis.
Troper Tales existing in the first place. Troper Tales was only created to keep tropers from writing their own tales on the main wiki. Troper Tales ruined the reputation of TVTropes and made the website a laughingstock of half the Internet. It was also known for attracting people who wrote stories that sounded creepy, filled with bile, psychotic, racist, sexist and ego-stroking. The admins could have either warned the tropers or banned them for writing personal tales instead of creating troper tales, since Troper Tales only reinforced the habit.
TV Tropes used to have a "strike format", but it was eventually disabled as people were using it simply to sneak in Take Thats and such. Texts that were previously striked are now hidden texts. The strike format however is still usable in the forums though.
Earlier there were "super secret spoilers", which was the equivalent of making the text white. This was also removed in part due to people actually using it for relevant information that reader couldn't see without highlighting the whole page.
, about heroes who heroically tried to stop villains and ended up making things worse than if they did absolutely nothing (Inglourious Basterds, The Ring, Kick-Ass, Con Air, Harry Potter and the Philosopher's Stone and Avatar).