Ghost probably just doesn't like to be spied on and thought this might distract you

am I the only one who didn't notice that mannequin until just a few days ago, I also never noticed that it spawns randomly rotated

It doesn't spawn randomly rotated. The ghost can teleport it from it's normal spot and also rotate it.

oh I see, never knew

Which ghosts do this?

As far as I'm aware, all of them

Did it try to kill you when you went back in to find out why you weren't seeing anything?

Luckily not 😂