They could be a bit exaggerated when you read about them, but i don't fully doubt them.
I do believe that demons do exist, because my grandmother's house has actually had one ever since the great depression.
Because alcohol was illegal at that time, the man who originally lived there hid whiskey bottles in the attic floor boards, and even though those bottles are long gone, you can sometimes hear the bottle getting clanked around. And i was told when my aunt was a kid the noise would keep her up, so my grandmother told her to tell him (His name was "Old man Yodders") to stop it, so she yelled at him to stop and go to sleep, then the bottles stopped clanking.
My uncle fixes up the house and has pretty much completely transformed the place, and it had made Yodders pretty mad, so once when my uncle was trying to sleep, his bed started to violently shake for a while.
Another instance was once of my uncle's friends was holding a stack of papers that then out of nowhere just got smacked out of his hands from nothing.
(I think "Yodders" is how his name is spelt, but I'm not fully sure)