Who ever decided what a demon looks like?

Ok so i got in a dispute with my girlfriends mom the other day. She said a picture i drew of my oc char for bleach looked like a demon. I asked the pastor of there church where in the bible what does a demon look like? His answer a demon has no earthly form. It is a spirit and noone really knows what it looks like. The pictures and stuff you see when you look demon up on the net or anything is pics people/humans made. So i wanna ask what does everyone else think?