from my own experience, it is often not positive though and paranormal phenomenon is mostly psychological but not necessarily hallucinative, which is the difference in understanding.
it seems to be mostly an aberration or dysfunctional release of the mind. this i've garnered from personal experience when there was much trauma, anger, violence etc as well as very manipulative sociopathic/psychopathic type people in the home environment. i noticed the paranormal phenomenon was taking place in a amplified, highly emotional/mental (but dysfunctional/abberrant) environment. this had nothing to do with 'ghosts' in the traditional meaning or the dead, it was very much due to the living and those projecting strong emotions and thoughts, especially aberrantly. i am not saying all such cases are negative, but most of them seem to be. some can be benign but those seem to be more rare.
i think most paranormal phenomenon that is negative is a byproduct due to a dysfunctional mind/thought-processes of whoever is emitting them, even subconsciously or unconsciously. literally, these are or were someone's ghosts or inner demons. Instead of using the mind in rational and healthy motives, it can operate in deviation.
We assume, because generally most people are operating rationally at most times but it's not the case at all times or with all people. there are very dysfunctional and twisted minds and this i think can emit negative personifications of that conceptual minds/thoughts such as demons, negative shadow figures etc. unfortunately, it can affect others around them as they are extensions and that is the main reason why it is even remotely worthy of not dismissing it simply as imagination.