Quip to Black used to be "Grissom One Liner" after Gil Grissom from CSI: Crime Scene Investigation. The old name required people to know the Grissom character, who was perhaps not the best known example even within the CSI universe. In turn, CSI was not the originator of the trope. Finally, the strong internet meme surrounding the CSI: Miami (Horatio Caine) version makes it all too easy to mistake the trope for the meme and vice versa.
Recycled Trailer Music was once "The Elfman Effect". Not a reference to Jenna Elfman of Dharma and Greg, nor to the Danny Elfman / Tim Burton collaborations, nor to the The Simpsons theme overshadowing Danny's other work. Readers who got the right Elfman had to then guess it meant that he is one of a number of composers whose music appears in trailers for films other than the one it was composed for.
Repeating so the Audience Can Hear was originally named "So What You Are Saying". It was renamed because it had nothing to do with the trope it described and sounded like a generic line of dialogue rather than a legitimate trope.
Repetitive Audio Glitch was formerly called "Like a Broken Record". The trope was renamed to be more in line with the actual definition (which is not metaphorical) and to avoid confusion with Broken Record (which is metaphorical).
Rhetorical Request Blunder used to be "Rid Me of This Priest" — from a famous oral tradition surrounding Henry II. His words were interpreted as an order to kill Thomas Becket — which they may not have been. The reference was quite opaque to some, others mistook it to mean the trope was about priests. The trope was also clarified as being broader than murders, but always a statement not intended as a request.
Romantic False Lead was originally "The Paolo", after the character from Friends. Renamed because it required knowledge of a specific work and out of a general trend away from "The X" trope titles.
Romanticized Abuse was formerly "Abusively Sexy". It was renamed because the original name suggested that the abuse could be a good thing.
Romantic Plot Tumor was formerly "George Lucas Love Story" after the poorly received romantic subplot in Star Wars Episode II: Attack of the Clones. It was renamed because making titles just to be a Take That against a single work (it was determined most George Lucas stories don't suffer from this trope) isn't very good form and it's very likely the name will stop being topical.
Rube Goldberg Device was renamed from "Robinson Goldberg Contraption" because a.) Heath Robinson and Rube Goldberg are two different people known for such devices, and b.) the term "Rube Goldberg Device" is in common use off-wiki, so there was no need to Call a Rabbit a "Smeerp".
Satellite Love Interest was once "Shallow Love Interest" and, before that, used to be "Shallow Female Love Interest". The first time it was renamed was because the latter had kind of a sexist ring to it and it being anywhere close to "female only" has been discredited time and again. It was renamed again due to misuse for complaining about love interests tropers didn't like.
Satiating Sandwich used to be called "Everything's Satiating with Sandwiches" according to the discredited and completely unrelated "Everything's Better With X" snowclone family.
Scandalgate was originally "Gate Construction". It was renamed for the sake of the page having a clearer name, i.e. following the Watergate-originated X-gate snowclone trend for scandals.
Schmuck Banquet used to be "Goldilocks and the Mines of Moria", which did not accurately convey the trope.
Sealed Evil in a Duel was called "Sisyphus vs. Rock" after the legend about the man doomed to eternal toil with no meaning nor respite by having to roll a rock up and hill every day to just see it roll back down in the evening. Notice how that is not really related to the trope.
Searching the Stalls used to be "Stalling for Time" — a name that was mistaken as meaning, well, stalling for time more often than it was used to mean someone searching a series of bathroom stalls.
Second Season Downfall used to be called "One-Season Wonder", which enjoyed almost 100% misuse (either as "series that lasted one season or less" or "great character who only appeared in one season").
Selective Enforcement was once "Flaming Cobra Sugar Cellar" (named by something happening on The Simpsons). Another case of an incomprehensible trope name, particularly since it wasn't named In-Universe (as evidenced by the use of a British English descriptor based on an American work).
Self-Constructed Being was called "Evil Seed Plot" for a short while after launching. We realized that it isn't limited to evil folk, seed-based regeneration or whole plots.
Shoplift and Die was once known as "Easily Angered Shopkeeper" before it was renamed to clarify that action was specifically caused by player shenanigans. Even before that, it was named "Izchak's Wrath" after one of the shopkeepers of NetHack.
Sidekick Song used to be "Hakuna Matata" after a song in The Lion King. People were using it for Hakuna Matata (the life attitude) which is what the phrase is best known for, not for songs sung by sidekicks. Hakuna Matata, meanwhile, was recycled as a different trope.
The Silver Age of Comic Books was formerly known as "Silver Age". It was renamed because not only did it need to be changed to match the new names for Golden Age and Dark Age, but there were also references to the concept of a Silver Age independent of comic books.
Sixth Ranger Traitor was once "Sixth Column". It was an exact duplicate of a work title. The work was not an example. The protagonist refers to the resistance movement as a Sixth Column: loyalists — the opposite of a traitorous fifth column. The new title clarifies the Sixth Ranger reference and avoids the indirect fifth column conflation by just saying they are a traitor.
Small Name, Big Ego was formerly known as "Ted Baxter". The former was originally meant to be a Real Life counterpart of the latter, but that turned out to be a bad idea, so it was locked and kept exampleless for a long time. Eventually the two were merged using the definition of Ted Baxter and the more descriptive title of SNBE.
The Snark Knight was originally "The Daria" after the eponymous show. It was renamed and slightly redefined after some confusion as to what the trope actually was, and the relative obscurity of the Daria character outside of the show's target demographic.
Snowclones was originally "Chekhov's Pun", but was being mistaken for a pun or joke used as Chekhov's Gun, and simply wasn't very clear.
Solve the Soup Cans was "Soup Cans" after a puzzle in The 7th Guest where a message must be spelt out using soup cans. It was renamed to give the sense of a weird puzzle to those unfamiliar with the reference.
The Something Force was formerly "Troper Force", but was renamed to not use the placeholder "troper".
Something Only They Would Say was "As You Wish" after a quote from The Princess Bride. Changed to avoid mistaking the trope for "a declaration of love that doesn't include the word 'love'", which is what the quote is more commonly known for.
Soul-Sucking Retail Job was renamed from "Super Slave Market" as it has nothing to do with slave markets or superpowered people.
Space Zone was once "Lylat System", a non-descriptive title that gave no clues to those who did not know the reference (the setting from Star Fox).
Spanner in the Works started life as Xanatos Gilligan, which required knowledge of two specific worksand of the once-ubiquitous "Xanatos ____" snowclone in-joke system to understand. As a bonus, the current name is commonly used outside the site as well.
Speaking Like Totally Teen was once "Get a Load of That Square". Renamed because the old title sounded like a line of dialogue and was hard to search for.
Speaks Fluent Animal was formerly "The Dr. Dolittle". It was renamed for being character-named and not thriving.
Stating the Simple Solution used to be known as "Why Don't You Just Shoot Him?" The trope was renamed, and the old name reworked into a supertrope, because the name was far too easy to use as a troper Catchphrase, leading to massive amounts of misuse.
Surprise Incest used to be called Incest Is Relative. The former pun-based name was too vague to really suggest what the trope was about, thus the rename, and Incest is Relative was turned into an index for all tropes about incestuous relations in fiction.
Surprisingly Sudden Death was formerly "Deadly Guest". It was renamed because the trope is a specific kind of death trope rather than a character one and the previous name was causing some misuse because of that.
Surveillance Drone was formerly "Magic Cam". It was renamed because the trope has nothing to do with magic.
Suspiciously Similar Song was "The Jimmy Hart Version" for a long time, named after a professional wrestling manager who would write those kind of songs. Obviously, it was needlessly obtuse to anyone outside of the wrestling fandom.
Teacher/Student Romance was originally named "Mary Kay Letourneau Teaches Here", after a highly-publicized real-world example. It was changed for being long, hard to spell, and difficult to use organically in descriptions. The new name, "Hot for Student", got eventually changed to illustrate it goes both ways.
Terrible Artist used to be known as "Hollywood Scribbling". It was renamed because it didn't really belong in with the Hollywood Style tropes and most of the wicks referred to a character who draws bad art.
Terrible Trio was formerly named "Team Rocket" after a well-known trio — although Jessie, James, and Meowth aren't known for villainy effectiveness.
Toplessness from the Back used to be "Sexy Back"; it was renamed because people were assuming it meant "back that is sexy". The "backless dress" subtrope put on the page because of the confusion was split to Sexy Backless Outfit.
Trojan Prisoner was formerly known as "Wookiee Gambit" after the scene in Star Wars Episode IV: A New Hope where Luke and Han infiltrate the Death Star's prison deck by bringing in Chewie in chains.
Tropes About Perverts was formerly "This Index Is Full of Perverts"; one reason for the rename presumably being due to the deprecated "This Index is X" naming pattern.
Trouble Magnet Gambit was "Vasor Gambit". The fact that you'll probably have to mouseover or click this link to find out where Vasor came from, never mind who he is, provides the reason for the change.
True Companions was formerly known as "Nakama". It was renamed for clarity and because the old name was based on the misconception that nakama means "people who are tied together by ties stronger than anything else" when it really just means "friends" or "companions".
Trust Password was formerly "I Am John Smith", named for a specific example of the trope from a multi-format Japanese series. It was changed mostly because "I Am John Smith" is a massive spoiler. In case you're wondering and can't resist finding out, said series is the Haruhi Suzumiya franchise, during an event in which Kyon travels back in time to meet Haruhi in the past, and identifies himself as John Smith to keep his cover when he meets her.
Tsurime Eyes and Tareme Eyes used to just be "Tsurime" and "Tareme". They were renamed to clarify that they are about eye shapes.
Turn the Other Fist was renamed from "McLintock Punch" because the old name was obscure and work specific and the trope itself was very underused.
Two Decades Behind was renamed from "Still the Eighties" in order to encourage uses of the trope for works that depict any settings that seem to take place two decades before the work was created despite supposedly representing the present.
Tyrant Takes the Helm was formerly "The Umbridge". It was renamed due to the Trope Namer being known for several other things than just the trope content, leading to confusion and misuse in examples and potholes.
Uncanny Village was formerly "The Village". It was renamed as per new policy that trope and media should not share titles whenever possible.
Unconfessed Unemployment was formerly "I Can't Tell the Wife I Got Laid Off", which was a line-of-dialogue title, and an overly long one, at that.
Undesirable Prize was formerly "Flokati Rug", and renamed for greater recognition outside the fandom.
Unexpected Gameplay Change was originally "Unexpected Genre Change". Changed to make it clear that the trope is specifically about gameplay styles in video games. However, the latter would get changed to Out-of-Genre Experience, possibly to avoid confusion.
Unexplained Recovery was originally "I Got Better". It was renamed because it was being constantly misused as a Stock Phrase and a generic pothole for "getting better" in general rather than the actual trope.
Unfazed Everyman was "The Arthur Dent". Renamed because it was named after a character.
The Villain Makes the Plot was once "The Law of Bruce", which failed the One Mario Limit. Are we talking Lee, Springsteen, Willis, Banner, Campbell, Wayne, Almighty or Robert the Bruce? (Answer is the third.) The title failed to provide context: readers who guessed the Bruce were no nearer to the trope.
Villain over for Dinner was renamed from "Did Mom Just Have Tea with Cthulhu?" to get rid of the dialoguey title and because it's not necessarily about a powerful being.
Virginity Makes You Stupid used to be "Innocence Virgin on Stupidity". It was changed to be more transparent, as most people didn't get the pun note Innocence "vergin' on" stupidity and simply thought the title had bad grammar.
Visions of Another Self was originaly masquerading as "Flashback Echo"; the new name is much more accurate to the description and allows a broader interpretation of the trope. A relaunched Flashback Echo ought to refer to the flashback version of Ironic Echo or Meaningful Echo, which is what some people thought this trope was under the old name.
Vulgar Humor used to be "Refuge in Vulgarity". It was renamed due to attracting complaining about works that employ this trope.
Wackyland was once called "Magicant", an area from EarthBound. It was renamed to be less obtuse and more encompassing.
Wake Up Fighting was once called "Rude Awakening". Another case of taking a commonly used phrase and using it as something that wasn't the trope, causing underuse and misuse.
Waking Up Elsewhere was renamed from "Waking Up in Vegas" because the trope was much broader than the former name made it seem... and because the Trope Namer wasn't even an example.
Watch It Stoned used to be called "Everything's Better on Drugs", which implied a connection to the unrelated and discredited "Everything's Better With X" family.
The Watson was formerly both "The Sarah Jane" and "The Rick", named after a companion from Doctor Who and a character from Magnum, P.I., respectively. They were merged and renamed because "The Rick" is just flat out too vague, the distinction between the two was too subtle, and Watson from Sherlock Holmes is well-known outside of Science Fiction and Eighties TV fandom.
Waxing Lyrical was formerly "Don't Sing Along If You Don't Know the Words". It was changed because it was too long and not at all descriptive of what the trope was actually about.
When You Coming Home, Dad? was originally "Cat's in the Cradle"; the new title is a lyric from the song which also provided the name of the old title. It was changed to clarify the meaning of the trope.
White Hair, Black Heart was renamed from "White-Haired Pretty Boy" due to constant misuse and because the trope is more about traits than characters.
White Magician Girl was originally "Staff Chick", which underwent lots of misuse with people adding examples that played the role of healers but didn't match the personality (you might be looking for Healing Hands, The Medic or White Mage for more general cases) or worse, people assuming the staff to be the crucial aspect of this trope. The new name also matches this trope's Black Mage counterpart, Black Magician Girl.
Wicked Weasel was originally titled "Everything's Better with Weasels", a snowclone of the discredited "Everything's Better With X" family. As with several similarly named tropes, the earlier name encouraged a list of all weasels regardless of portrayal.
Wife Husbandry was originally titled "Hikaru Genji Plan" but was changed since the latter was too obscure to those not knowing said work.
Wimpification was originally called "Ukefication"; it was changed to remove Gratuitous Japanese and because the trope was not actually about relative positions in a relationship as much as the stereotypes that went with them.
Windows of the Soul was originally "She Then Saw the Glint of Triumph in His Eyes", which was too long and unwieldy.
Word Salad Title is now the primary name for "Super Punk Octo Pudding Gas Mark Seven" instead of a redirect. This is because the original name was too hard to remember and spell, couldn't be used in a sentence, and didn't make all that much sense (which was both a problem and the entire point).
World of Pun was "A Worldwide Punomenon": The original trope was very poorly defined and was being incorrectly used as a Pothole Magnet for puns; when the definition was clarified and tightened, the name was changed to reflect that and to help reduce misuse.
World of Weirdness was "Planet Eris", which didn't have anything to do with the various meanings of the word "eris".
Yarling was called "Nose Yodeling" and was renamed because Yarling is the more accepted term.
YMMV used to be called "Subjective Tropes". It was renamed from Subjectives when someone pointed out that tropes are not subjective, and renamed again because people say "YMMV" more than "it is subjective", and because YMMV is an easy to remember namespace.
You Are Too Late was formerly "Thirty Five Minutes Ago" after a line from Watchmen comic book series. It was renamed because it was not only completely opaque and unsearchable, but also a major spoiler.
Youkai was formerly "Yokai", with the latter now redirecting to the former, because the latter is wrong according to standard transliteration conventions.
You Know Who Said That was renamed from "And Now You Know the Rest of the Story" because the trope name was an obscure reference that didn't even fit the definition.
Young Conqueror was renamed from "The Alexander" because the name "Alexander" alone was not distinctive enough to clearly refer to Alexander the Great. Further, while Alexander the Great is noted for conquering a large part of the (known to him) world, the fact that he started out as a teenager is less widely known.
Your Mom was originally named "Yo Mommas a Trope", which was perhaps the ugliest use ever of the word "trope" as a placeholder in a trope name.
Yuri Fan was formerly "Yuri Fanboy". It was changed because too many of the examples and Troper Tales were female for the male-gendered title to make any sense as the primary title, though the original title was kept as a redirect.