They say when you have a bad trip on drugs, that you are actually entering into the lower astral realm where you attract negative entities. I don't mess with acid or any hard drugs. I would only touch natural entheogens like cannabis, mushrooms, and salvia. My theory is that when you have a bad trip on natural entheogens, that means it is revealing something to you. As Bob Marley said "when you smoke da herb, it reveals you to yourself".