It sounds that the use of psychedelic substances should be done with some cautions; maybe similar to the ones advised to having safe astral travels, since the risks are pretty much the same: Low entity attachments on the consciousness and aura.
I think the kind of trips or experiences that one person can get from the use of psychedelics are almost unlimited. Sometimes you have a spiritual experience, other times a more expanded experience of the normal life here on Earth... Sometimes, with some substances you get astral travel, but many times you dont, you just get inner insight, etc. It is very hard to classify these experiences or to know what is going to happen exactly.
I think that our own state of consciousness is what makes the difference between a good and expanding experience or a bad one with the beings that you are mentioning. After all, what most of these substances do is to expand your awareness and to show you what it is that you have inside your deeper mind; the beauty and the ugliness.
In my personal experience and choice: I like to take psychedelics from time to time (once every few months) and my experiences with them have been mindful every single time so far. I have seen negative entities attached to me on some occasions but with these psychic visions I have had a deeper awareness that they cannot really hurt me more than I let them. That in reality, I have the power over my own consciousness, even if at the moment I have my weaknesses which have attracted those entity attachments.
Also, while you are under that state, you get super energy sensitive. I think you can easily know if a spirit who is interacting with you is positive or not by feeling its energy and looking at the colors of its aura. If its a spirit which is fooling around with you, I think you can feel the negative vibe, as well as you can feel the loving energy when it is a loving spirit or guide. Energy does not lie and by feeling you can know a bit about the intentions of the spirits you interact with. However, this also depends many times on your own energy levels; according to your state of being, you attract similar kind of presences. For instance, if you have a lot of fear while you are having the experience, then chances are you may attract fearful entities to your presence. If you have a positive, relaxed mindset while you are having this experience, then you attract very positive energy. This is why the setting and company are so important. This is why it is a good idea to do it in clear spaces, hopefully beautiful or in the nature. Good music, good company, physical security, positive mindset and stimulants can really make the difference. Basically surround yourself with beauty and positivity and it should be a very beautiful and mindful experience. I usually ask for protection from Source before I take any psychedelic substance. By connecting to the love field, it can be a good way to keep nasty things away.
Everything is energy, frequency and vibes. Surround with the good ones and the nasty beings wont have an entering point. Also, your own energy, the higher your own energy frequency is, the better.