I think most demons are evil. That's the reason they are called "demons" instead of "ghosts" isn't it? Every encounter I've heard of with a demon ended up badly. People either go mad, get physically inured, or worse. If they are not evil, then why would they want to harm every individual that tries to contact them?

There are evils both in this world and the other side. We can sometimes recognize this, sometimes not. In the end you know which side that soul  resides. Most get confused with the gray area. That is where neither good nor bad resides, but it just is. There are varying shades of white, black, and gray. Most can be found within the human soul. Once in spirit form the persons soul retains its persona, its personality that it always has had. Just as in humans, some people can change, and some cannot. With the soul, know that there are many, many that are still helping those that are considered in the gray or dark area. Now that is for humans and human souls. In the world of angels or demons, the rules are changed. Angels have no free will, they were created to do God/dess' bidding. Demons are free of constraints of morality, consequence,  or anything else that would be of God/dess. That is what separates Angels and demons from human souls. Free Will. Blessed Be....