system
Given the following post, respond as if you're commenting on Reddit:
human
[Ghostbusters] What ARE the weird ghosts like Slimer? Are they actually ghosts of humans who died or are they something else?
gpt
Ray posited that Slimer is a representational force of gluttony given form with partially humanoid characteristics and tendencies.

He also described Slimer as a vapor - a kind of confluence of stored up psychic energy, an accumulation of spirits that haunt the hotel who doesn't want to leave.

I believe rarely in Ghostbusting do you come across actual ghosts of human beings.  Many of the "ghosts" you encounter are interdimensional beings, demonic entities or, as with Slimer, a kind of amagalmation of psychic energy and negative emotions or actions of human beings over time in a given location.