I experienced the "darkness" as a lack of connection. And by that, I mean lack of connection to Source, to Oneness, to Consciousness. So anything in this world that disrupts that connection, or occludes your path back to Source, I would categorize as "not for your greatest good". That's not to say that it is evil or wrong. Just that it will make it harder for you to regain the connection or strengthen it. And once you've experienced it in it's full expression, you won't want to do many of those things that take you away from it or block you from it.
RE: Mother Ayahuasca - Finding My Voice