Angels and Devils Hidden on Earth

Born spirits can take many forms in order to hide on the mortal plain.
Devils will often come to Earth disguised as humans, humanoids, crows, rabbits, and dogs (often either a hairless Mexican dog breed, or a black dog), among many other forms. Most often, they are on Earth to be cruel to or try and trick mortals, primarily for their own amusement.
Angels will oftentimes take the forms of humans, humanoids, doves, and cats, among others. Their appearance seems to be mostly to ward off Devils, and to offer people kindness and peace.

Ways a Spirit may be Recognized

A disguised Spirit may be recognized if they...

Are glowing
Have glowing eyes
Disappear suddenly and without explanation
Display very unusual behaviors, such as walking upright as a four-legged animal
Don't appear entirely accurate to what they're meant to be

Disguised spirits are thought to be the source of many urban legends, such as that of fae and changelings.