It's hard to say for sure. Some people believe them completely, while others think they are just made up or exaggerated.
I don't think they're all true. Many of these stories could be the result of people wanting attention or trying to explain strange events in a supernatural way when there's a more logical explanation.
Well, it's a bit of a mixed bag. Some paranormal witness stories might have elements of truth, but they could also be influenced by people's imaginations or misunderstandings. There's often not enough concrete evidence to prove them one way or the other.