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.
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 couldnt 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.