As to the shampoo question, here’s my take.
As far as I know, in most of the areas of the world that the people here represent, shampoo is the norm. It’s considered weird or something to not use it. Almost everybody uses it, and nearly nobody questions it. With an almost religious devotion, just about everyone squeezes something (they don’t know what!) out of a plastic bottle, and massages it into their hair, for a solid 5-10 minutes or more, almost every single day of their life. And, if you’re crazy enough to say that you don’t use it, many questions follow, for the most obvious example an incredulous, “Then how the hell do you keep your hair clean?” Of course virtually nobody wants to hear that something that they’ve been doing forever has been a completely useless (and maybe even counter-productive!), religious ceremony, accomplishing absolutely nothing but distributing some money to a sham industry. But, at the same time, their natural curiousity overwhelms them: So they keep asking for clarifications, and they listen.
But let’s try to be more charitable: Most people, at some time or another, independently tested whether using shampoo was worthwhile. Everybody remembers going on a trip without any shampoo, and finding that their hair went to hell in just 3 days. Everybody has experienced sleeping over at a friend’s place for a few days, and forgetting about all of their hygienic habits: Their teeth go to shit. They smell awful. Their hair becomes an oily, disgusting mess. And so on. And so forth. Hell, every teenager wakes up almost every morning to a waxy chaos on their head. And everybody understands that just 5-10 minutes with the shampoo sets everything back to normal. A few moments with it, and everything’s all right. I mean, how could it be a religious devotion, if everybody has independently verified its utility at one point or another?
Well, here we discover the real insidiousness of shampoo: Stop using your shampoo for 3 days, and your hair becomes shit. So you admit your mistake, and get back with the shampoo habit. But stop using it for 6 weeks, and what happens? Everything’s fine. Wait those 6 weeks, and your hair will be cleaner and healthier than ever. You simply have to get through the initial, painful correction. (Doesn’t that sound familiar?) But most people mistake the correction for the problem. They think that they’ve verified its usefulness, but all that they’ve done is seen what the recession (the correction!) would look like, and ran the opposite way: Their only reaction is to pump more shampoo into the system: to try to keep the boom going. Or something. Well, maybe the analogy is breaking down at this point. But, either way, here we reveal the real treacherousness of shampoo: It creates the problem (dries out your hair by destroying a lot of oil, and your body starts trying to compensate by producing more oil), and then once it wears off it suggests itself as the solution (Shampoo: “Too much oil? I’ll destroy it for you!”). It compensates for itself. Just trick enough people into starting up with it, and it’ll take care of the rest. It pretends to offer to clean your hair; but all that it does is make you dependent on it.