OBEs are pretty interesting. Some are obviously hallucinations, people prove it is not the real thing by shuffling a deck of cards when in body, and then checking the deck when OBE. If the cards in the two experiences don't match, the OBE is not real.
On the other hand, there are stories of hospital OBEs where patients actually learn confirmable information about the real world that they had no way of knowing if they did not really have an OBE. One example I've heard a couple times is a lady who saw a green tennis shoe on the roof of the hospital, and someone later went up and found it.
It is also interesting to learn the underpinnings of the Frankfurt school. I had thought they were communists of some sort, but communists are just as materialistic as the fascists they dislike. So, I guess they are a bit more nuanced in their views.