Demons do not cause any negative phenomenon on SS, nor for people who aren't yet dedicated. In the latter case, at worst They will be dismissive or not really give you much attention.
They will not cause any negative phenomenon, unless the individual is blatantly attacking them or blaspheming them in vile ways (doing a blood sacrifice or similar lunacy), because They want people to know Them, learn about Them and reach out to Them in the proper ways. They show great patience even with the uninitiated for those reasons.
Only enemy thoughtforms or entities will cause such attacks, in order to try and scare people away from approaching the Gods or knowing the Demons.
They pretend to be Demons while doing harm to you and plague your mind with negative imagery in an attempt to get your mind to associate these scary and unpleasant experiences with the Demons, so that you are scared and avoid them.
Don't be fooled by these scare tactics of the enemy.