Can Demons be ghosts??

Alot of people know about Demons whether it be through television or other media but there has been a strong link between Demons and ghosts. There is a type of haunting known as a Demonic haunt which are very dangerous and usually do not like human beings.

One theory is that these Demonic Haunts are due to a Demon attempting to matiralise on this plain of existance but not having enough energy to do so.

I would really like other peoples opinion on this

I don't see why not. Some theories about ghosts are that they used to be humans who died, and couldn't leave this plain for one reason or another.

Why should a demon be any different? A lot of demons certainly have enough rage to keep them here as an emotional anchor.