I will answer you from my own experiences, although there is much controversy on this. I want to remind you first that we honestly don't know exactly what we are talking to! We assume these are spirits based on our history, religious teachings, and other's experiences in the past, but we honestly don't know.This brings me to another question that will help me. Does a "negative energy" always mean demonic or can it be something less than demonic
Assuming these energies are spirit forms, my experience is there are negative energies that are not demonic but they are dangerous as some may wish to attach to you. Not a good thing. There are also some energies I've run into I feel are demonic...they are a very different "feel" to them...almost oily, slimey and very dark. Either way, you don't want any of the negatives to communicate with you.