Footprints of Muck

Remember when your parents wanted to keep the floors in the house looking nice and clean so they'd remind you to wipe your shoes off before you came in?

In this instance however, the focus is more on who or what made these footprints rather than why the floors are dirty. Because, lets face it, when a series of footprints suddenly appear in the form of the deep red color of blood or some other watery/dirty/mucky substance...it is...rather unsettling...to say the least... Especially when you can hear the accompanied sound of the footsteps ringing throughout the area, but you can't exactly make out who or what is lurking nearby until you turn around and come face to face with it...

If the person making the footprints is evil or something similar, the muck that is covering their legs and feet will make them look even more out of place and therefore creepier.

This trope is typically used to increase suspense. Therefore it happens in horror or drama themed works.

Foot Focus typically comes into play here. If the footprints appear to have been made by a werewolf or some other sort of beast then it's Human-to-Werewolf Footprints.

Examples of Footprints of Muck include:

Anime and Manga

A version happens in the first Kara no Kyoukai movie with a puppy dog that walks by the main character tracking blood. We then see the body of someone who just jumped off a building and the resulting pool of blood.
In the opening sequence of Higurashi no Naku Koro ni, Rena walks on some broken glass and drips blood onto the floor.
Elfen Lied: Lucy in the beginning of the first episode where she's naked and walks through the pools of blood of the people she slaughtered and in the second episode when she's fighting Bandou.
- In the tenth episode after she kills Kouta's father and sister, she's seen standing in a pool of their blood.
This also occurs in Howl's Moving Castle, when Howl turns into his true form and leaves wet footprints across the floor, waking up Sophie.

Comic Books

Done subtly on the first page of Watchmen when the red-head prophet-of-doom walks casually across the puddle of the Comedian's blood, trailing bloody footprints.

Film

The Ring did this with Samara after she came out of the television, in the form of water from an old well.
Played entirely straight in The Last Samurai, when Tom Cruise walks in the Japanese house with his boots on, and he realizes when he sees his host cleaning the muddy footprints behind him that this just isn't done.
In the movie Constantine, when Satan appears in a fairly well-dressed manner, but his feet are bare and covered in muck.
Played for laughs in Scary Movie II. The characters find a trail of bright red footprints leading down the hallway, prompting one of the male characters to comment "Ew! Someone's on the rag!"
This happens in the Fathers Day segment of Creepshow.
In the 1941 film Cat People, there is a trail of muddy animal prints that turn into a human shoe prints.

Live-Action TV

The Goodies. In the Kitten Kong episode the Comic Trio follow the huge paw prints of Tinkles the Kitten across London on their three-seater bicycle, and keep running into things because the giant purrball can just step over objects they can't.

Video Games

Child Alma in the first First Encounter Assault Recon game.
Silent Hill. Several of the games, if not every one of them. The first game and some of the others actually measure how far your trail of monster-blood footprint is.
- In Silent Hill 3, there are disembodied bloody footprints acompanied by the sounds of a crying young girl that lead you past a few obstacles and help you find hidden areas. No explanation is given for this.
Scrying in Clive Barker's Undying will sometimes show bloody footprints, showing you how to get through some puzzles.
Doom 3 pulls off one scare by having bloody footprints appearing out of nowhere as something invisible walks away from you towards a locked door.
You do this in Second Sight if you step in blood, and the Mooks freak out accordingly, particularly if you're in their line of sight but invisible.
In Kuon, if your character walks through a pool of blood they will trail bloody footprints for a while afterwards.
The Footprint Passages in Yume Nikki. This being a Surreal Horror game, there's no explanation, but it's still creepy.

Web Animation

At the beginning of Exmortis 2 the player encounters an invisible being that reveals itself to you by treading across the floor with bloody feet.