To be completely honest, it's not a requirement that you experience something for yourself to be able to judge it. Some things are just obvious. The fact that drugs and alcohol are primarily bad is obvious to me, based on what I've seen and heard from people all around the world. One of my close friends and former classmates has a brief history with some kind of drug, I know. She's a raver. It's inevitable that someone offers you one of them mitsubishi pills or whatever. She tried, and regretted it soon after. Apparently, the trip itself is not worth the knowledge that you're messing up your own brain and potentially subjecting yourself to the risk of becoming addicted to something you don't want to and can't afford to use regularly. How about that? A long-time teenage raver who tried drugs at recommendation from her raver friends and decided it's more fun without them. Raves, especially, I guess, because the experience in itself can be extremely trippy even without drugs.
Like Space Giraffe on the 360. Holy damn, that game has brainwashed me. Everyone hates it at first, unless they've been closely in touch with the developer diaries and stuff. But within a couple of hours, to a couple of days, people just flip around and go "best game ever". And I almost agree. I agree it's the best thing of its kind. It's the ONLY thing of its kind. If you like to feel like an alien substance is taking over your brain and destroying it from inside - try Space Giraffe! Once you get the hang of it, you start LIVING in this crazy acid world, and you'll feel really out of place when you finally stop playing and go back to real life. Honestly, I bought it the second I finished playing the trial version. I don't even know WHY I bought it. It took me two days to figure out why I bought it, and now I'm glad I did. I just wish I had more time to spend on it, and less flatmates to freak out if I were to turn up the volume...