Romance-Inducing Smudge

Best friends Alice and Bob are eating together, when Bob notices that Alice has gotten a bit of food on her cheek. Saying "here, let me get that for you", Bob reaches over to wipe it away with his thumb. The breathless Alice, having carried a torch for Bob for a long time, looks into his eyes and he into hers. Slowly, they lean in closer...

The Romance-Inducing Smudge is any kind of smudge, stain, or blotch that causes one character to help clean it off of another, which leads to a romantic moment between the two. This serves as an excuse for the characters involved to get closer together than they otherwise normally would, and the ostensibly innocent touching involved is almost sure to increase romantic tension for the pair.

The stain need not be food related, though this is frequently the case. Similarly, the offending smudge need not be limited to an individual's face: a stain on their clothing that a potential object of affection must rub out can work perfectly well for this purpose, among other things.

If both people involved catch on to the mood of the scene, this can lead to a First Kiss between them. It is not uncommon, however, for the pair to be interrupted at the last second by someone else barging in or by one of the characters losing their nerve. Either way, this can work as a sign that one or both characters have feelings for the other, or serve as more fuel for the Will They or Won't They? fire.

Often used as a form of Ship Tease. Compare with You Taste Delicious, when one character decides to lick a smudge off of another, and with Finger-Suck Healing.

Examples of Romance-Inducing Smudge include:

Film

Spoofed in Rustlers' Rhapsody, where the cattle baron's daughter has been dragged behind her horse for hours. When Rex rescues her, she has only a tiny smudge on her cheek to show for it, which Rex tenderly wipes away.
Inverted in The Mummy 1999, where Imhotep's romance with Anakh-Su-Namun leads him to smear her body paint.
A variation in Zombieland: Columbus discusses how his life's dream is to brush a girl's hair behind her ears.

Literature

This happens early in the Left Behind series, when Chloe is eating a cookie and has a bit of chocolate on her cheek. Buck leans over and wipes it off with his thumb, then eats it on impulse. Cookies later become a romantic symbol for them.

Live Action TV

Buffy the Vampire Slayer: A rare romantic moment passes between Willow and Xander in the season two episode "When She Was Bad", when Willow gets ice cream on her nose as the pair are walking past a cemetery. As Xander leans in to clean it for her, the two look like they are about to kiss... until a vampire pops up behind Willow, forcing Xander to attempt to hold it off and killing a Squee-inducing moment for Willow x Xander shippers.
- Willow later attempted to invoke this trope by putting ice cream on her own nose, but Xander, now once again distracted by Buffy, simply says "You got something on your nose."
Parodied in the How I Met Your Mother episode "World's Greatest Couple", where Brad freaks out Marshall at dinner by licking his napkin and wiping a smudge of food off his face.
A mild variation is invoked in Parks and Recreation between Leslie and Ben after the latter has dust thrown in his face as a fake Native American curse-lifting ritual.
In the "Love And Monsters" episode of Doctor Who, Rose's mom used this trope on Elton to get him to take his shirt off.
Averted in a famous sketch by German comedian Loriot. He tries to seduce a woman in an Italian restaurant, but happens to have a piece of noodle in his face. When she points it out, he removes it, but the next time he uses the napkin, the noodle returns to his face. Hilarity Ensues as the noodle moves around. No, he doesn't get the girl.
Played straight in the ITV adaptation of Northanger Abbey; Henry cleans a splash of mud off Catherine's face after they've been out riding together.
A moment like this happens (oddly enough) in The X-Files episode "Red Museum". It was odd because it was supposed to be in the time period in which Chris Carter was adamantly denying any romantic feelings between Mulder and Scully. While investigating a case in cattle country, the two decide to eat at a local rib restaurant. In the middle of talking about the case they're on, Mulder just reaches over with a napkin and wipes a smudge of sauce off of Scully's face. Though taken aback, Scully graces him with a shy smile.
Firefly example. In Objects In Space, Mal tried to examine the blood stain on Inara's lip from where Jubal Early struck her. The spark of when Mal's hand touches Inara's lip is all but visible.
Scrubs: Towards the end of "His Story II," Elliot cleans the last little bit of clown makeup off of J.D.'s face (long story). Ten seconds later, cue makeout session.
In the Glee episode "Wheels", Puck and Quinn have a playful food fight while making cupcakes for a bake sale. Puck goes to wipe flour off of Quinn's cheek and they lean towards each other... then Finn walks in.

Theatre

The song "A Stud and a Babe" from the musical I Love You Youre Perfect Now Change features one of these in the middle. Subverted, because he doesn't actually do anything but tell her about it, and the romance fades fast after he does.

Guy: You, uh... you have some nacho schmutz on your face.
Girl: (wipes) Gone!
Guy: You, uh, you wiped it to the... other side. Now it's on your chin... better?

In the song "It Won't Be Long Now" from In the Heights, the character Vanessa pauses to tell Usnavi he has "some schmutz" on his face and tries to wipe it off. He shyly tries to move away and the two stand there awkwardly until Sonnny appears and starts dancing with Vanessa.

Webcomics

Subverted in El Goonish Shive, where Ellen goes to wipe a smudge off Nanase's face and she freaks out because she was having trouble admitting her attraction to Ellen, and moments like that only made it more awkward. Add to this the facts that Nanase used to like it when her last ex-boyfriend (Ellen's brother) did stuff like this and that the napkin was tucked in Nanase's blouse.

Western Animation

In an episode of Young Justice, Me'gann accidentally spills all kinds of stuff on Superboy while trying to make dinner, which of course induces her to attempt to clean him up...and then right when they are about to kiss, Red Tornado walks in and they spring apart across the room. Superboy still with everything on him, staring at TV static. Yeah, not obvious at all.