A person who is revolting to look at, as they may have a busted grill for instance, basically this person looks like spew after a big night on the turps, or looks like a vulture has been given several hours to mutilate the face of this hideous beast.
"Geez mate! That bird you picked up looked like a half-eaten pasty"
"That girl last night had a decent body, but the face was a fucken half eaten pasty! I still fucker her though..."