Another angle on this is that it isn't about humans in general, it's about some of the most gullible humans.
This seems to imply that there is something fundamentally different about these humans compared to other humans. I'm not convinced this is the case. I would be rather surprised if you couldn't make the average human drink bleach by exposing them to specifically tailored situations/information.
That's not just arguing from fictional evidence, it's arguing from hypothetical evidence. I don't know, but I've been told that you can get a room full of Jews shouting "Sieg Heil" with a sufficiently rousing version of this. [1] You could probably get people to drink bleach by mislabeling a bottle.
Getting back to the general point, it's not just important to know that an aspect exists, it's important to know how strong it is.
[1] I was told it either by or about Robert Aspirin/Yang the Nauseating. He was quite a good performer.
We can always use more case studies of insanity that aren't religion, right?
Well, Miracle Mineral Supplement is my new go-to example for Bad Things happening to people with low epistemic standards. "MMS" is a supposed cure for everything ranging from the common cold to HIV to cancer. I just saw it recommended in another Facebook thread to someone who was worried about malaria symptoms.
It's industrial-strength bleach. Literally just bleach. Usually drunk, sometimes injected, and yes, it often kills you. It is every bit as bad as it sounds if not worse.
This is beyond Poe's Law. Medieval blood draining via leeches was far more of an excusable error than this, they had far less evidence it was a bad idea. I think if I was trying to guess what was the dumbest alternative medicine on the planet, I still would not have guessed this low. My brain is still not pessimistic enough about human stupidity.
http://en.wikipedia.org/wiki/Miracle_Mineral_Supplement