Ace Lightning: Jessica Fisgus, during the dance at the end of the first season.
Andor: In "Announcement", Vel meets Kleya in-person on Coruscant, looking almost unrecognizable with her hair out of its usual practical updo and styled nicely with tasteful jewelry and fashionable urban clothing that stands in direct contrast to the roughhewn Aldhani work clothes she'd been wearing during the run up to the heist. "Nobody's Listening" sees this as essentially her default state of dress, being the cousin of Chandrila's senator.
Angel: In "Waiting in the Wings", the titular character scores tickets for the opera. Everyone cleans up well, but Fred and Gunn, both of whom are probably the least upscale fashionable, seem to attract the most attention — especially from each other.
In the episode, "The Tale of the Closet Keepers", the resident tomboy, Kiki, gets one of these. When she is revealed to the Midnight society by Betty Ann, she even gets a whistle from Gary and Tucker incredulously says, "I don't believe it! You look like... Like a girl!"
Happened again in "The Tale of the Mystical Mirror" which featured a girl starting work in a beauty shop. After a bit of primping by the owner, the girl walks out in a stylish black dress with full hair and make-up to the glee of her two co-workers. She's back to her normal clothes when she finishes work however.
The first few times Felicity Smoak removes her glasses and lets her hair down, it's presented this way. Especially the first time when she goes from office work clothes with a ponytail to a cocktail dress with curls, and her crime-fighting partners Oliver Queen and John Diggle take a good few seconds to recognise her. Not that she wasn't attractive before, so "cleaning up" becomes a common occurrence from the second season onward.
Also shows up briefly with Sin, normally an androgynous Tomboy in gender-neutral leather clothes. To pose as a hooker to catch the Villain of the Week, she dons a figure-hugging short skirt and heels (borrowed from Thea Queen, no less) that show off her legs.
Delenn is always lovely, as per her Lady of War status, but her usual clothing is Minbari and, while quite beautiful, isn't all that revealing. So when Delenn has dinner with John Sheridan and puts on a human-style black evening gown, Sheridan is lost for words.
She does it again two seasons later in "Atonement." This time the gown is even more revealing, and Sheridan — who is deeply and openly in love with her by that point — has an even more pronounced reaction.
Battlestar Galactica (2003): The sight of Starbuck in a long slinky blue dress instead of her usual military-issue tanks or flight suit renders Apollo quite literally speechless. Lampshaded by a previous exchange between them where he teases her about her (lack of) hygiene, and she tells him she cleans up nicely sometimes. Though it should be noted, Starbuck is an Unkempt Beauty anyway, and Apollo was attracted to her long before the clean-up.
Male example: Sheldon is known for his collection of Superhero shirts and when he has to be formal wears awful, multicolored suits. When Penny forces him to get a better a suit he looks absolutely stunning, earning a Jaw Drop from Penny and whistles from the audience.
A straighter example: Amy typically wears rather dowdy clothing with a long skirt and shapeless sweaters (along with Mayim Bialik's self-described "ethnic" looks), but in part due to Penny's influence she sometimes manages to dress up for special occasions and catch others off-guard with how well she turns out. Fans also noticed how attractive she became in the Nurse Chapel costume while "Playing Doctor" with SheldonStar Trek-style. She also wasn't bad looking as Snow White either when the girls hit Disneyland. In the Grand Finale episodes, she undergoes one more makeover with help from Raj, who takes her shopping for new wardrobe, after she complains about how frumpy she looked in the photographs after seeing pictures of herself in magazines, resulting in a stunning transformation (though Sheldon disapproves due to his aversion to changes in general).
The Biggest Loser: Most of the contestants for NBC's show are quite good looking once they achieve a healthy weight.
Black Books: In one episode Bernard enters the room wearing a pure white suit, looking incredibly dashing. He then furiously begins to yell at Manny, revealing that this is the real colour of his normal black suit, which Manny's mother had the nerve to wash!
Blindspotting: Though Ashley usually looks nice anyway, everyone is awed when she's dressed up in a wedding gown.
Bones: Happens (sort of) when the title character descends the stairs in an awful bridesmaid's dress. Her main love interest says she looks "nice", until Cam helps her fix the dress to be prettier. He then tells her that she looks "gorgeous" to which she simply complains "I thought you said I looked nice before!" Then in the Halloween-themed episode "The Mummy In The Maze", Booth has a similar reaction to seeing Bones in a Wonder Woman costume.
Boy Meets World: Played With in one episode. Topanga suddenly becomes self-conscious about her looks, and decides to get a makeover. However, Cory and Shawn recognize that she was already beautiful before getting "cleaned up" and now with the makeover she will be "mega-beautiful", and sure enough she stuns them when she walks out of the beauty parlor. At the end of the episode she decides not to keep up the new appearance because it's not who she is.
The Boys (2019). In "You Found Me", Kimiko locks herself in the bathroom and puts on clean clothes, brushes her hair and does her nails. Frenchie is noticeably charmed when she comes out. That is until someone throws a grenade through the window...
The Brady Bunch: One episode had this as a plot point for Jan, the middle sister. She's wondering why boys — and one boy in particular — don't show any interest in her, so she has one of her brothers ask the particular boy what he thinks of her. He casually answers, "She's a good guy." Jan gets the picture, dolls herself up, and ends the episode with a Grand Staircase Entrance before the boy in her girly clothes.
In the same episode, Buffy attempts to get Willow to do the whole "coming down the staircase" thing to impress Xander, albeit dressed as a hot goth rather than a fairytale princess. However, Willow backs out and chooses a traditional Bedsheet Ghost costume. At the end of the episode when Willow finally works up the courage to wear the outfit, the dressed-up look has the desired knock-out effect - not on Xander, but on imminent love interest, Oz who spots her from his truck (in fact Oz catching sight of Willow in unusual outfits and being intrigued by her is something of a running joke in the run-up to their actual meeting)
Played straight with Willow and Xander in the Homecoming episode. Later spoofed in a callback to that same scene when Xander is about to get married, Willow in her bridesmaid's dress looks at him in his tuxedo and comments "Good thing I realized I was gay, otherwise, you, me, formal wear... bad combination."
Subverted again in "Inca Mummy Girl" in which the gang are having a world cultures themed costume party and Willow turns up wearing an Eskimo costume and Xander of course only has eyes for the Monster of the Week Ampata dressed to the nines. Willow remarks that maybe she should have worn something sexy instead but Oz is playing on stage and this following exchange happens:
Oz: Hey, that girl. Who is she? Devon: (talking about Ampata) She's an exchange student. I think she's from South America. Oz: No, not her. The Eskimo.
Giles is clearly impressed when Faith shows off her look for going undercover at a formal party, a Pimped-Out Dress with cleavage.
Fair Cop Kate Beckett is told this explicitly using the trope name on at least two occasions: the high society fundraiser in "Home Is Where The Heart Stops" where she and Castle go undercover and the book launch of Heat Wave in "When The Bough Breaks". They're not wrong, either. The first time is a 'nervous and shy' example because she's wearing an amazingly expensive and beautiful dress that Castle has bought for her; the second time, everyone assumes she's a character actor hired to play 'Nikki', the character based on her.
Also, in "A Death in the Family", Alexis in her prom dress combines this with a She Is All Grown Up moment for her father.
Cheers: Frasier starts salivating with desire when Lilith, who normally sports a criminally tight bun, lets her hair down.
Control Z: Sofia is beautiful, but mostly doesn't comb her hair or dress in flattering clothes. When she dolls it up for a party, she really shines.
Dårfinkar & dönickar: Simone, having been masquerading as a boy at her new school, turns up to class in a dress and lipstick. Subverted in that Isak, her crush, decides he likes her back after finding out she's a girl, but before he's ever seen her in girls' clothes.
Dark Angel: Word for word. While there's the obligatory slow-mo pan up Max's dress, she's the one who says "You clean up nice" to Logan and he just says "So do you."
The Dark Crystal: Age of Resistance: Technically it's a disguise, but Deet dresses in some elegant finery to get an audience with the All-Maudra and looks rather nice. Unfortunately, Seladon sees right through the disguise instantly.
Dead Man's Gun: In "The Highwayman", Robert Cosgrove uses some of the money he stole to buy his wife Brenda a fancy dress and insists she wear it at dinner that night. Brenda is astounded by the looks and compliments she receives from the boarders.
Degrassi: The Next Generation: Given the age most characters are introduced at, and how long they remain in the series, most will have this moment if they aren't introduced as stylish (which is most of the cast). Usually it goes hand in hand with She Is All Grown Up, male and female. Both of the Van Zandt siblings pulled this, just compare Liberty and Danny's intro looks to their last appearances, and Clare got this as a plotline.
Played straight in "The Romans": Ian changes into Roman clothing and a slightly drunk Barbara says he looks "splendid", even helping him style his hair correctly to fit the costume. It goes to his head a bit and he gets quite into pretending to be a Roman.
In "The Macra Terror", the usually very scruffy Second Doctor is put in a futuristic beauty-therapy machine that styles his hair into a neat parted style, pampers his skin and cleans and presses his clothes so that he looks immaculate. Polly is bowled over and calls him "gorgeous", but he expresses some reservations about the new look ("who wants to see their own face in their shoes?") and immediately dives into a "rough and tumble machine" to put himself back to normal again, to Polly's extreme disappointment.
Inverted in "The Deadly Assassin", where when the Fourth Doctor is forced to don the elegant academic robes used by his native culture as formal dress and looks an absolute disaster, with his underwear showing and his frizzy hair poking out from under the lopsided headdress. But when the Time Lords put him in prison clothes — a crumpled poet shirt, red corduroy trousers and scratched-up knee-high boots — he looks about as dashing and romantic as he ever gets to. And even gets a bit where he gets wet.
Played straight in "The Talons of Weng-Chiang", when Leela gives away her clothes and is given a dress by Jago to replace it — and when the Doctor sees her in it, he's actually left speechless in mid-word. Then he suggestively offers to buy her an orange.
Subverted in "Enlightenment". Tegan changes into Gorgeous Period Dress to the amazement of everyone. Except the 5th Doctor, who doesn't seem to notice. Much to Tegan's annoyance.
Played straight in "The Unquiet Dead". Rose is ordered to change from her 21st century clothes into something a bit more appropriate for the Victorian period. The Doctor is impressed.
Martha compliments the Tenth Doctor a lot when he puts on a tuxedo in "The Lazarus Experiment", and they both compare his look to James Bond. Not that the fangirls mind his usual natty pinstripe-suit-and-canvas-sneakers get up either.
The Dukes of Hazzard: While the non-canon 2006 TV film had a backstory of how a nerdy Daisy Duke became Hazzard County’s hottest hottie, the Season 7 premiere of the original series, “Happy Birthday, General Lee” had a different backstory of how Daisy went from homely to become the prettiest girl in Hazzard. In this Whole Episode Flashback about the General Lee’s origins eight years earlier, Daisy simply wears pigtails, button-down checkered shirts and overalls ... until she gets a job at the Boar’s Nest, lets down her hair and puts on her iconic pair of cutoff shorts to wow all the men of Hazzard.
A Coy-and-Vance era episode, “Coy Meets Girl,” had an episode where Daisy turns the tomboyish Bobby Lee into a ravishing young woman. (This, while the “fake Dukes” try to hide Bobby Lee from two armed robbers after she witnesses one of their criminal acts.)
Extraordinary Attorney Woo: Young-woo is a very naturally cute young woman, but she doesn't put much thought into her appearance, wearing professional but unstylish clothes to work and favoring comfort above all else. She also wears little makeup and doesn't do much with her hair. Her Love Interest Jun-ho first starts getting heart eyes over her when he sees her trying on a wedding dress whilst undercover. Between the high-end, elegant gown, the help of the stylists, and a little rearrangement of her hair, she looks absolutely lovely. Young-woo doesn't notice or care about her transformation or Jun-ho's reaction to it, and just wants to get on with the investigation so she can put her own clothes back on as soon as she can.
Firefly, Kaylee, the ship's mechanic. In episode "Shindig", some high class women at the party snark at Kaylee for wearing a store-bought dress, but she is happily vindicated when one male partygoer comes to her defense (and later the men are delighted to discover how tech-savvy she is). It is also inverted many times with Kaylee, with Simon saying that she dirties up nicely. He says she's especially cute when she's covered with engine grease or fuel.
Rachel's season five Love Interest Danny is introduced with a massive beard and bushy hair as a result of a lengthy mountaineering trek that makes him look, in Rachel's words, like a yeti. When he cuts his hair and shaves the beard Rachel doesn't initially recognise him because he looks so different.
When Rachel (who is very beautiful all the time) heads out for her first night out with the girls since having her baby Emma, she is even more careful about her appearance. As Ross puts it: "You clean up good!" "You clean up good" is how the trope is usually phrased in Westerns.
Frontier Circus: In "Stopover in Paradise", Ben romances a tomboyish ranch owner. She eventually decides to start wearing feminine clothing, evoking this trope (although she does a Femininity Failure when it comes to walking in high heels).
Talisa Maegyr is shown to clean up nicely, without all the blood and gore that is.
While the gaudy pink gown doesn't suit Brienne well, she still looks somewhat pretty in it, which is more than we can say for her book counterpart. In the novels, the pink dress makes Brienne seem more unattractive. Suffice it to say the leather tunic and blue riding skirt she wears during her time in King's Landing suit her far better.
Glee: Plays this straight with Quinn and Finn in the episode "Prom Queen", and Quinn does look amazing, though it's hardly a revelation since Quinn is generally said by many/most to be the prettiest girl various characters have ever seen/met (former said by Finn during said walk down the stairs, latter said by Rachel in the same episode).
Gotham Knights (2023): In "Belly of the Beast" when Duela puts on a fancy dress along with doing her hair, Turner is briefly stunned at seeing her. Though she's pretty, Duela's usually much less concerned with her looks, so it's definitely noticeable.
Good Luck Charlie: Tomboy Jo, in "Duncan vs. Duncan", turns up on the doorstep in a dress for the cotillion, prompting a jaw drop and "wow" from Gabe.
Gotham: The first time that Bruce invites Selina to a Wayne Foundation ball, Alfred sends some "proper" clothes to her to wear. When Bruce sees her for the first time, he is stunned by her appearance; she reacts the same to him, being the first time seeing him in a tux.
H₂O: Just Add Water: In one episode Zane buys tomboy Rikki a dress for her to wear at a dinner party at his house. Emma is at the dinner and her jaw drops when she sees Rikki walking down the stairs in the dress with her hair down. She's seen wearing dresses more frequently afterwards.
Hana Yori Dango: In this live-action drama, Tsukushi originally comes to Shizuka's party, she's the only one not in a stylish dress. After getting pushed into a swimming pool, Shizuka dolls her up with much make-up, hair pampering and a beautiful dress. Needless to say, she finally gets everyone's attention.
Hannah Montana: Inverted in the episode, "You Are So Sue-able To Me". When Lilly's crush Matt asks her to the school dance, Miley convinces Lilly to get a Girliness Upgrade to impress him. When she later shows up at school with her new look, she has quite a few guys drooling over her, but then she gets stood up by Matt. It turns out he preferred her tomboy look.
Haven: Audrey Parker is so inept at picking out pretty clothes she has to have elderly bachelor brothers do it for her but she wears them so, so well.
Healer: Ahjumma usually loafs around her computer lair around in pajama pants and unkempt hair. When she dresses up to go out in public, however...
Hotel Hell: Karan of the Town's Inn, after receiving a makeover, looks decades younger. Not only that, but she also becomes much more confident and assertive.
How Do I Look?: This is the entire premise of this show. Take a woman whose friends don't like her fashion sense, buy her a new wardrobe, change her hair and makeup, and show her new look to a crowd of her friends and family as She Cleans Up Nicely. Often, the show gives a useful gift to the woman (besides the clothes, hair and makeup) such as paying 1/2 the past-due mortgage debt so a woman and her kids can stay in their house.
I Am Not Okay With This: Syd doesn't usually care much about her looks, but puts on makeup and a nice dress for the dance (though she's hardly bad-looking to begin with). Dina compliments her on it.
iCarly: The focus of the episode "iMake Sam Girlier", both played straight and subverted. Sam is feeling down about her tomboy/ladette image and decides to get a Girliness Upgrade to impress a boy she likes named Pete. She looks quite good in her more feminine outfit, prompting an audience reaction, and even though Pete is quite smitten with her new look, he reveals that he actually liked her tough girl image better. However, there have been other times in the series, before and after this episode, that Sam has put a dress on, and she looks quite good in them.
Janda Kembang: The tomboy Wulan decides to wear feminime clothes and goes to Salmah for a make-up for once in her life because she plans to confess her feelings to Malik. Every guy she meets, including Malik, is awed.
John Adams: Abigail Adams spends most of the first few episodes in rather plain dresses. When she does the makeup hair and nice dress thing at Versailles, her husband is lost for words. Truth in Television, adorably enough! When Gilbert Stuart mentioned that he "wished to God he could have painted Mrs. Adams when she was young; she would have made a perfect Venus," Mr. Adams expressed emphatic agreement.
The Lord of the Rings: The Rings of Power: Halbrand follows the classical "return of the king" make-up but with a sinister turn, but for the Southlanders. First time he is introduced, he is lost at sea, gaunt-looking, tired and wearing rugged clothing. Nothing about him up this point says he is a king material. After a few days in Numenor where is regains his strength, he receives from the Numenorians a full suit of regal-looking armour, and goes from wandering vagabond to instantly looking like a king. He even physically resembles Aragorn from PJ's trilogy. By the end of the season is revealed that he is Sauron, whom Galadriel finds at a very low point in his life.
Lost Girl: Kenzie in one episode when she pretends to be Hale's date for a Fae gathering.
Love Thy Neighbour: The normally dowdy Joan Booth is allowed a moment of glamour in Eddie's Nightmare Sequence about being stranded on a desert island where Bill is the all-powerful native king, reminding the viewers that Kate Williams was really quite attractive and was only playing a downtrodden frump.
The L Word: Shane actually looks very nice wearing a dress and with her hair down, though it was only for going to Carmen's cousin's quinceañera as this is really different from her normal style (she puts it on reluctantly to attend).
The Magnificent Seven: Recurring character and tomboy Casey Wells is persuaded to put on a dress and fix her hair in order to impress JD. It works... for all of ten seconds, at which point she steps on her hem, tears her skirt off, and is left standing in her bloomers.
Married... with Children has a heavily implied male example. Kelly's description of Eric, whom she played a mean prank on him that resulted in him having a toe amputated during their high school years, early in the episode "Blond And Blonder", is that "even his glasses had acne". Come the night of the class reunion, he looks absolutely handsome, fancy, and without glasses, much to the shock of Kelly once he reveals himself.
Kelly: Eric Waters? Y-You look different.
Eric: It's amazing how your looks can improve with nice clothes, contact lenses, and 10 million dollars. *walks away*
Kelly: *goes back to her group of girls* Ten million dollars? Oh my God, he's the ex-husband of my dreams.
Iron Fist (2017): In the fourth episode, Danny Rand finally gets some good clothing of his own, and is dressed in a suit and tie for the press conference announcing his return to the public. Joy Meachum can't help but comment:
Joy Meachum: You clean up pretty good. Ward Meachum: ...The tie might be a touch effeminate.
Daredevil (2015): When Frank Castle takes the stand at his trial, he's been fitted out in a suit. Foggy can't help but comment, "He looks better than I ever have and he's not wearing a tie."
M*A*S*H: Subverted to the point of parody in the episode "Stars & Stripes". Margaret likes Sgt. (busted to Pvt.) Scully, whose attitude toward women is, shall we say, less than enlightened. To prove to him she's a woman along with being a Major and a Head Nurse, she gets all dolled up in an outlandish pink prom gown with Stepford pearls, high heels and lipstick. He appreciates it so much he flops down on her bed and asks her to (literally) cook him an omelet.
Princess Elena, once the Sidhe is removed from her body.
Gwen, any time she gets dressed up during the first four seasons. Special mention goes to "Queen of Hearts" where Merlin is momentarily stunned into silence when he goes to pick her up for her date with Arthur. The fandom had a reaction like this too when the first on set photos of Queen Guinevere appeared online before Season 5.
While Van Pelt already looks pretty sharp in her work attire, when she really dresses up to pretend to be co-worker Rigsby's girlfriend for a sting, she drives the poor man to distraction.
And Lisbon, who is often overshadowed by Van Pelt, has one of these moments at a society fundraiser that she's been ordered to go to because the CBI is broke. Jane, UST-ee/unrequited love/co-worker seems not to notice, but then he isPatrick Jane, and probably thought he could screw with her in some way by not mentioning it. Made better by the fact that when she gets called away to a crime scene, she just sticks her regular leather jacket over the top and looks eccentric and beautiful.
In The Mighty Boosh, Howard has a subtle moment of this in the series three episode The Chokes. Normally he wears ugly, unfashionable and clashing clothes in various shades of brown, but after finding confidence as an actor thanks to a Training Montage, he walks into the Nabootique with his hair neatly combed while wearing flattering black clothing and a dapper hat. His bisexual best friend Vince, who is hinted to be in love with him, doesn't say anything, but the way he looks him up and down from head to toe with a mixture of surprise and lust on his face certainly implies he was thinking this trope.
In My Mad Fat Diary, Rae is this for Archie’s date in 'Touched', after Chloe and Izzy's makeover for her.
Her appearance at her mum's reception in 'It’s a Wonderful Rae:Part 2'.
Happens with Fran at one point though the shock may have been due to her dress being quite garish as well as sexy. Many episodes got use out of Chateau Sheffield's sweeping staircase.
The very first episode shows that Devi can easily make herself look as glamorous as "an Indian Kardashian" when she chooses to and when she volunteers at the last minute for Paxton's sister Rebecca's fashion shoot, he comments on how good Devi looks in the designer clothing she wears..
While she's pretty regardless, Fab looks very nice indeed in a dress once Eleanor gets her to reluctantly put this on. She soon reverts to her original style though, disliking this.
New Girl: This is Schmidt and Coach's reaction when they see Jess in the Little Black Dress her friend Cece helps her pick out... a reaction which is killed soon after, when Jess breaks into a celebratory dance.
The Outpost: In the finale, Talon marries Garret wearing a dress and with her hair in a wavy style. Though she's hardly unnatractive, they make her look especially lovely.
Pee-wee's Playhouse: Reba the Mail Lady is rarely seen out of her postal uniform. There have been at least two exceptions, however. First, she dresses up nicely in "Party" (Pee-wee lampshades that he has hardly ever seen her out of uniform). But that's nothing compared to the second time she dressed up: in "Rebarella", in preparation for her date with Derek, Miss Yvonne gives Reba a beauty makeover so that she looks a lot more like Yvonne herself! When Pee-wee first sees Reba's new look, he is appropriately agape with amazement.note It's also the final episode to feature Reba (not counting flashbacks).
Pennyworth: Once Katie Browning (Jessye Romeo) is at Peggy Sykes' place, there's a quite striking difference between before and after her change of haircut and clothes.
Charlie in the episode "Sex and Drugs", when she is given a nice dress to wear instead of her usual shirt and jeans, as part of a honey trap.
At the end of the episode "Home", Tom Neville appears in a suit. He is a male example of this trope.
Robin Hood: In the BBC's show, tomboy Djaq glams up in order to infiltrate Nottingham castle. The scene features both the possible outcomes mentioned in the trope description: Will is reduced to a staring, stuttering mess and receives a somewhat sharp Moment Killer response, while Allan manages to be a little more smooth, pays her a compliment and gets the gratified smirk.
The Sarah Jane Adventures: "The Wedding of Sarah Jane Smith" gives one of these to Luke Smith, who is rather stunned to notice that Ranidoes clean up nicely. Actually, he has one right after the other - first for his mum Sarah Jane, and then for Rani. (This version, obviously, is purely platonic on both counts.)
On the rare occasions when Stevie puts on a dress, she turns everyone's head, especially David.
In Season 6, Butch Lesbian Ronnie shows up to the premiere of Moira's film in a stunning cocktail dress and rocks the red carpet.
Sherlock: Molly Hooper puts on a gorgeous dress for the Christmas party in "A Scandal in Belgravia". John is visibly impressed, and Lestrade's jaw hits the floor.
Season 1, Tempest, Chloe dressing up to go to the Spring Formal with Clark.
Season 4, Spirit, a possessed Lois descends the stairs at the Kent Farm in one of the most hideous dresses ever seen — Clark catches sight of her and gulps. There was also perhaps a better example from season eight's Bride, where Lois comes down the same staircase in her formal wear as maid of honour at Chloe's wedding; Clark comes to meet her at the bottom in his formal wear and they both seem silently impressed.
Spaced: Parodied mercilessly in the finale. Daisy tries to make this an Invoked Trope (including a memorable sequence where she extends a lipstick accompanied by the Star Wars lightsaber sound effect) and at first appears it's working, but then it turns out that the men were actually ooh-ing and aah-ing over a spectacular flaming birthday cake behind her.
Special Ops: Lioness: Cruz wears unflattering rough clothes then later military fatigues early on, but easily spruces herself up into flattering outfits when getting close with Aaliyah, who's quite rich.
In a way, they got to this by the 3rd episode by forcing Carter into a Mongol concubine dress. No staircase, but she starts the scene with her back to the camera; after the dramatic turnaround, her teammates have few words to say.
Vala Mal Doran also does one of these in "Bounty". Of course, the only person who pays any attention to her is Cam's friend Darell.
Star Trek: Voyager: The first two episodes of the fourth season ("Scorpion, Part II" and "The Gift") presented us with the gradual transformation of the character Seven of Nine, from a zombie-like Borg drone to the show's ultimate Ms. Fanservice.
In Stranger Things, the boys have to dress Eleven up as an ordinary girl (i.e. a non-psychic who hasn't been imprisoned in a Government Conspiracy lab all her life and consequently has learned basic social cues) in order to sneak her into school. Everyone — especially Mike — is impressed with the results.
The Suite Life of Zack & Cody: Zack is persuaded to take tomboy Max out on a date. She appears at the restaurant in a nice dress with her hair done up and Zack's jaw drops.
The Summer I Turned Pretty: When she's all dolled up for attending the debutante ball, Jeremiah's stunned by how good Belly looks.
While the brothers Winchester are hardly chopped liver even at their slobbiest, in the episode "Red Sky at Morning" the costume designers very wisely put Dean in a tux and had him swagger down a staircase to the sounds of Bond music. Dean expects his date, with whom he has Belligerent Sexual Tension, to mock him. Instead, she stares open-mouthed and suggests that they have "angry sex" later.
And then they go dropping Dean into the 1940s for an episode, with him being specifically dragged into a suitmaker because his usual jeans, flannel shirt, and jacket combo won't work in that time. Dean would look good in a paper bag, but when he steps out in a perfectly fitted suit and fedora, it's even better than the tux.
Also done with Castiel after returning from purgatory and shaving. Dean even shifts awkwardly in his seat at the sight. The actual costuming is just a return to his normal Unkempt Beauty baseline, but the scene itself is presented exactly like a She Cleans Up Nicely reveal from a teen romcom, complete with a sexy pan up his body and much to the amusement of the fanbase.
S.W.A.T. (2017): In "Never Again" Chris show this. She's good-looking, though she normally wears utilitarian work clothes or fairly ordinary ones when off duty. Here, she's shown in a highly flattering black spaghetti strap top that's quite revealing, and really shines.
Taxi: Inverted Trope: Elaine asks Jim to go to a fancy party with her (out of concern for his feelings and with major reservations). He shows up at her door groomed and shaved, in a neato tux. Elaine gasps "You're gorgeous!" He replies in his quavering burnout voice "Yeah, I never get tired of hearing that."
Trigonometry: Ray mostly wears drab and unflattering outfits before Episode 4. When she gets dressed up and does her hair for the wedding, she looks far prettier than usual.
The Twilight Zone (1959): In "Two", after washing her face and putting on the dress from the department store window, the woman looks beautiful. The man is clearly smitten.
Ugly Betty: Mark's boyfriend Cliff has one of these at Bradford and Wilhemina's wedding, causing Amanda to quip "Who knew there were hardwood floors under that shag rug?"
One of the few things the otherwise disappointing That '80s Show managed to do well by making Chyler Leigh nearly unrecognizable in goth makeup as June Tuesday so that on the one occasion where she wasn't done up that way her natural beauty actually showed up very well.
The West Wing: Leo says this to Congressman Matt Santos...no, it's not Ho Yay, it's just meant to be taken literally.
Wings: In one early episode, Helen decides to wear a sexy dress to a cello audition. When she doesn't get the job, she isn't sure whether it was because her cello playing wasn't good enough, or she wasn't sexy in the dress. She shows Joe what she looks like in the dress, and after noting his reaction, she promptly hurries off to practice her cello some more.
In the episode "Karl's Wedding" of Workaholics, Adam is accosted by a homeless woman named Rachel trying to steal his beer. The two have a screaming match that quickly turns into a strange meet cute, and Adam takes her to the wedding, dressed up and actually looking fairly attractive-despite still having an overall druggy look and demeanor. The fact that Rachel was played by Katee Sackhoff helped.
Working (1997): Parodied. Chris is one of many applicants for a newly opened position under the male chauvinist boss at the office. Chris prays on the boss's good-old-boy tendencies and general machismo to land the job. The show's main character (along with the audience) soon discovers that Chris is really a woman in disguise: Christine. When Christine outs herself, in the sauna, accompanied by all the company's execs, she returns to the office looking quite sexy in a skirt-suit. Cue one of the male characters saying "That's Chris?! He sure cleans up nice!"
This is one of the premises of this Colombian telenovela. Although she doesn't get "princess pretty" at the end, her appearance definitely improves during the series.
This happens in the many spinoffs too (such as Ugly Betty).
Young Riders: Louise "Lou" Macloud has to keep her gender a secret from most folks, but on one occasion she gets a chance to dress like a girl and wow her teammates.
. The full shopping trip is a Funny Moment as Sheldon tries on progressively worse suits.
