If people continuously walk/drive over the same part of grass/snow it would start to wear down and leave a trail.
Bloody footprints left by people who are bleeding.
Footprints in snow.
Wet footprints when stepping from a wet surface to a dry surface.
Dirty footprints (from dirt).
Dirt/wet/bloody smudges when you melee something.
Dirt/wet/bloody smudges when interacting with things, for example leaving a smudge on car doors, or leaving a smudge on a table that you took an item from.
Disturbed grass/bushes/shrubbery when someone walk on/through it.
Note: it’s all simply time based, trails/footprints/smudges disappear after a while.
After leaving water or a wet surface you dry off after a while.
You stop leaving dirt footprints after being off the dirt/sand for a while.
Stop leaving blood everywhere after you stop the bleeding (or a little while after you stop it).
I think that about covers it.