Well, it would be scary if ghost appeared in their mutilated forms, but if you think about it, why would ghost even appear with their mutilated forms? Most of the time, their last image of themselves is how they think they would look like, so as a ghost, they would look exactly like that, not with an arrow running through their head.
What I'm saying is the scary ghosts, unless the person who died literally looked like a scary person or a monster, wouldn't have a ghost form that looks scary or with a lot of gore. They would quite literally just look like how they normally look or how they look the last time they saw themselves (or how they see themselves).
I the ghost looks scary and tons of gore, it must mean that either its not a ghost, or that its been a ghost so long, it forgot how it looks like.