First, here's what you know by the title of this blog post. At one point on the TV Tropes wiki a trope existed which was named "Slytherin House". If you've heard of Harry Potter, then you likely understand the reference. The question is, what does this trope refer to? Go on and take a guess before reading any further.
If you're anything like the majority of users who participated in this rename proposal, you probably came up with "not technically evil organization that nonetheless holds most of the story's villains as members". It's a popular enough topic of discussion for those who enjoy over-analyzing children's literature. It's what I thought the trope was about when I first clicked on the proposal. In actuality, the trope was about how in many works of fiction "ambition" is pretty much code for "evil". Those familiar with Harry Potter may recall that while the unifying characteristic of all Slytherin appears to be evil, in-story, the Slytherins' calling card is that they're all ambitious. Usually in trying to achieve some sort of evil goal, which is where the confusion tends to set in.
Slytherin House was a great annoyance to people when it was first proposed, mainly because it defied our expectations. Usually when you see a bad trope title, the logic behind how it came into being is relatively obvious. I've already mentioned tropes named after characters or directly after works of fiction. Here, however, was a trope name whose logic sort of made sense (in that I can see a bunch of Harry Potter fans in YKTTW, discussing how evil is ambitious in fiction, and coming to the obvious conclusion that Slytherin is the best possible example of this), but which completely broke down once the fact was registered that even to Harry Potter fans, coming to this page cold you're expecting a completely different trope.
The need for change was obvious. The forumites, however, were much like those of us from YKTTW in that they were doubtful our own authority and ever desirous to be "neutral". Many users made a point of saying that this title may have been defensible if it was about the first trope we all thought of, the not-technically-evil organization. This was true, and also a sentiment I generally agreed with. Direct references to works of fiction are frowned upon, but the not-technically-evil-organization trope is really hard to describe succinctly. Even if we had agreed to change that trope's title I can't imagine what new one we would have come up with. By contrast, you can probably guess what we renamed Slytherin House to even if you've never seen the page- Ambition Is Evil. Those two words are pretty much all you need.
I'm not sure anyone actually bothered to defend the title. The Harry Potter reference possibly, but as to the title itself everyone I can think of confused it for being the non-existent trope instead, and we had a long discussion where everyone pretty much agreed on all this several times until someone (probably me) finally took the trouble to rename it. In this respect the above-mentioned equivocation may sound a little much- it must be noted that due to the constant friction between pro and anti rename factions any excuse at a middle ground was jumped at. The acknowledgment of a hypothetical situation where Slytherin House could be grandfathered in was an act of good faith.
While we were finding ways to build new bridges in this new time of forum-centered renames, unfortunately other ones were lost. Because that trope, the one about not-technically-evil organizations? I remember thinking at the time that that would be a good trope to propose and possibly launch, but the subject managed to slip my mind. Now that I was dividing more time between the Trope Rename forums and YKTTW these things were easier to forget, and as far as I know, that trope still hasn't been classified yet. It was even mentioned that should this new trope be created it would probably make sense to give it the Slytherin House redirect, just so things would be less confusing.
Still, success is success, and now that we had an entire list of rename proposals (instead of just burying them in the midst of YKTTW), it was nice to go to the forum, look at old topics and go "yes, we actually managed to accomplish something there". That kind of consensus, where agreement is straightforward and we've even educated ourselves on hypothetical, non-existent tangent issues, has always been my favorite. Practically speaking, of course, it's not an outcome we can really expect all the time. It was still nice when it came up.