Tropes Are Tools, but some have aged better than others.
Over the course of time, a trope may be overused, misused, opposed, made obsolete, subverted on many notable occasions, or just end up being widely disliked. Eventually, a trope may reach the point where it becomes one which nobody should dare use seriously and only belongs in parody, satire, homage or pastiche. Often, if one of these is used straight, people will assume it's a Red Herring.
In some cases, a trope may be discredited due to changes in our knowledge of history or science. Use of the trope in fiction may change to reflect this. See the Time Marches On index.
This is not bad writing because the writing itself is bad, but because the writer doesn't know its audience. After all, Tropes Are Not Bad.
Omnipresent Tropes are immune to being discredited, mostly because those tropes are too natural to the medium of storytelling to ever be considered tired cliches. Undead Horse Trope describes tropes that have been subverted and parodied dozens of times, but aren't quite discredited.
Dead Horse Trope, where subversions or parodies outnumber straight use in recent works.
Forgotten Trope, which describes tropes that aren't used in recent works at all; they may have been considered Discredited Tropes years ago, or just fell from use for other reasons.
Compare Discredited Meme.
Please put examples on the trope pages as it messes up the indexing.
Barbaric Bully: Heightened school security in the post-Columbine era means that beating a kid up in a crowded school hallway usually comes with consequences. Not to mention that the advent of cyberbullying and the recent rash of bully-related suicides proves that a good deal of bullying is psychological rather than physical (and that psychological bullying can be just as harmful as physical bullying).
The Bermuda Triangle: No matter what anyone wants to say about Real Life ships and planes that have disappeared in the region, aliens, Cthulhu, dimensional portals, Atlantis, etc. are NOT behind any of it. The incidence of Real Life disappearances in the area is no higher or lower than any other part of the ocean that has similar size, weather, and maritime traffic.
British Royal Guards: Never used for anything other than comedic effect, but nowadays the once common gags involving a guard's effort to remain still under immense pressure have been replaced with ones where voluntary movement on the guard's part is observed, side-stepping more commonplace expectations.
Christmas Cake: Along with its Western variant, the Old Maid, it's not quite gone from consciousness, but it is on its way out, thanks to changing attitudes about the role of women in society, and increased education for girls.
Cut And Paste Note: In modern fiction, due to the prevalence of more convenient and harder to trace forms of anonymous communication. If used in any sort of forensic drama, you can bet the CSIs will admonish the culprit as an amateur and get damning evidence off the note.
Cut Phone Lines: Largely discredited in any story set after the widespread adoption of cell/mobile phones.
Declarative Finger: Often used by the authors to imply that the character doing so is just trying to come across as profound, which in turn is used to imply that the character is actually saying something NON-profound.
Phone Trace Race: Still used on occasion by very dense Hollywood hacks, but with caller ID, the popularity of shows like 24 which have mostly ditched this trope, and a general paranoia about Google and Facebook tracking your every move, writers nowadays tend to err on the side of the FBI/NSA/CIA being too good at tracking your every move.
Although due to Values Dissonance in the United Kingdom and censorship concerns - the new opt-in system proposed by the British Government, it's not quite a discredited trope yet and still played straight in countries where censorship is a Discussed Trope.
Santa Claus Tropes: Santa has become such a commercial icon of Christmas and as such overexposed via countless Christmas specials and merchandise, that it is pretty much impossible to play any trope related to him straight now, unless you have a really young audience in mind or have no self-respect for yourself as a storyteller.
Shotgun Wedding: A combination of greater availability of contraception and a reduced stigma of single motherhood make this trope seem very dated today. If a woman does get pregnant, a couple doesn't have to get married, but the father is expected to provide some form of support.
Standing in the Hall: Parodied in some Japanese works still; but not used in Real Life as much. In western countries, similar variants aren't used due to kids taking it as an opportunity to wander around the halls.
Stern Nun: For one thing, many teachers at modern Catholic schools are laypeople, not nuns. For another thing, after the advent of the Self-Esteem Movement of The Seventies, parents would be all up in arms if a teacher (whether a nun or a layperson) meted out those kinds of punishments.
The Generation Gap has pretty much become this, with Generations X and Y becoming parents and today's children growing up in an unusually similar cultural landscape to the one their parents grew up in. Fortunately, recent shows like Modern Family and Two and a Half Men have realized this, and thus, the trope has been gradually phased out of television and movies during the past decade-and-a-half or so. Today, it's relegated mostly to parody, although even that is becoming old hat.
Alliterative Name: A trope popularized by Stan Lee so that he could remember all these characters he co-created. It's been taken to the point of parody.
In a Big Damn Heroes moment, the villain is struck from behind. He'll then turn around and ask "WHO DARES?!" before a head to head battle breaks out. Now it's only brought up for others to make fun of it.
The Thing's "It's clobberin' time!" line is never played straight anymore. Most characters say the line for him, while others (Hawkeye) insult him for not coming up with any other lines in his decades of superhero work.
Hawkeye: Oh, we're still pretending The Thing isn't annoying? Spider-man: Ben?! He's a great guy... Hawkeye: He needs some new material. [...] Thing: It's clobberin' time! Hawkeye: Of course it is...
The thought bubble as a form of emanata has fallen out of favor since the eighties. It is now widely considered to be cheesy and has been replaced with captions.
Captions themselves are starting to become a bit of a tired cliche, as many comics with large casts will abuse them as a work around for straight narration of the action on-panel. Crack open your average JSA trade and marvel (lawl) at how many rainbow-colored soliloquy boxes you see per page.
"From this moment on, we shall be known as...": or any variations when characters or teams are deciding what codename to give themselves. Nowadays, comics may follow the cinematic trend where codenames are either eschewed in place of real names (even if the codename is given) or used in an offhand manner. Codenames may also be accidentally imposed on characters or teams.
"Doctor" or "Captain" in the codename: Having a Doctorate means little to the general public in today's climate. Even Doctor Doom has dropped the Doctor part from his name for the most part.
Superheroes Wear Capes: Time was when every other superhero had a cape. These days, capes are considered to be impractical, and even dangerous (see the fate of Dollar Bill in Watchmen or Edna Mode's speech about cape-related mishaps in The Incredibles). You'll still see capes on plenty of DC heroes such as the Superman family and the Bat family, but mostly because of the Grandfather Clause. Aside from Doctor Strange and the supervillains Magneto and Dr. Doom, Marvel has very few characters who wear capes.
Said Bookism: In these days, it's often considered redundant.
Prolonged Prologue: Often seen in fantasy novels. They give a lot of backstory on a world that the reader hasn't read enough of to care about yet. Most publishers say Show, Don't Tell and let the reader learn about the world through the eyes of the characters.
Live Action Television
The line "Hi, honey, I'm home!" was a stock standard phrase in many American family sitcoms from the 1950s and 1960s. Back then it was used straight forward, but since then it has been discredited due to its corniness and unrealistic routine. It is also a tad less believable now that there are far more women with families in the workplace (and even many stay-at-home dads), meaning that a man coming home from work to greet his wife isn't nearly as universal and routine as it once was.
The album art for Dance Hall Crashers' "Honey, I'm Homely" parodies this, with a woman cringing in terror from a sinister looking man entering her home, bearing a bouquet of flowers.
30 Rock also parodies this, when Tracy explains that he never does the same thing twice. Flashback to him doing the line "Honey, I'm home!" on the first take but then changing it with ever iteration: "Pacman, I'm Jewish! Jeffrey, we lost the tournament!""
Dinner with the Boss: This rarely happens in real life. If it does happen, it's at a restaurant, not at home.
Battle Of The Sexes episodes. Given that it's almost impossible to make such an episode without a ridiculous amount of gender stereotyping, and (to avoid offending anybody) they almost always end either in a tie or in one gender somehow handing the game to the opposing gender, this plot is rarely (if ever) used anymore.
Truck Driver's Gear Change: It's become such a cliche, especially during the second half of the twentieth century, that it's now almost impossible to play it completely straight anymore.
Digital Piracy Is Evil: Despite still lingering today, companies have ultimately realized that the war against piracy is a lost cause, and have taken incentive to work around it instead. More recently they have been pushing a new bill (s.978, Protect IP, SOPA) to put an end to piracy forever, although all attempts so far have failed. Although in the United Kingdom, the Digital Economy Bill may keep this as not quite a discredited trope, as it seems that public opinion is against the bill, despite politicians' attempts at copyright law changes. Values Dissonance, indeed.
That Reminds Me of a Song: Modern musicals, at least in theatre, are specifically not supposed to play this one straight anymore, though there's still a chance a song of this nature may end up as a Breakaway Pop Hit
Monster Closet: In first-person shooters. Present in shooters in mid 1990s to early 2000s but mainly replaced by offscreen or onscreen spawning.
One Bullet at a Time: Subjective; was originally a technical limitation, but can still be enforced for gameplay reasons (e.g. prevent some forms of Spam Attack).
Random Encounters: As a remnant of technical limitations of video games and its tabletop origins, they're lately replaced by other methods to engage a fight.
Some games made in RPG Maker play with this trope, by having the "Random Encounters" actually be regular encounters, but with the wandering monsters being invisible.
Retro tabletop-style games are sometimes used in some games where they fit the flavor better. Additionally, some pretty big games such as Fallout 3, many MM Os, any dungeon-crawler patterning itself after Diablo, and most of the JRPG genre still use these types of encounters. This may be an Undead Horse Trope instead.
"I Want" Song: This became discredited for a while after Disney and its competitors milked the Broadway musical cartoon formula for all it was worth — the makers of Toy Story even intentionally avoided this, in order to distinguish it from those films. That said, there's enough nostalgia left for it now to allow it to return in recent films like The Princess and the Frog, but it's nowhere near as prevalent as it was in the past.