Certainly true, but I feel like you always know when you have some issues lurking in the back of your mind. I once did some hallucinogens after going through a breakup and a small bout of loneliness in which I wasn't entirely happy with myself. Needless to say, it wasn't a fun trip at all. I tried to convince myself I was fine and in a good place, but with any real introspection, I should have known I wasn't in the right mindset going into it.