Often when I am visiting someone and use their shower, they say that I should use their soap but I don't think to ask which bottle, specifically, is their shampoo/soap. I don't think to ask because these things are labelled, right?
Except that many times when I'm looking for bottles that say "Shampoo" or "Soap", I instead find an assortment of bottles labelled "Body Wash", "Bath Gel", "Bath & Shower Cream", "Bubble Bath", "Herbal Treatment", and host of other names. Some of these are soaps, some are conditioners, and some are neither (moisturizers, scents, bubbling substances). There's a code. I don't know the code.
Instead, I recently noticed that what I almost absentmindedly just look at the ingredients. I haven't taken an organic chemistry class or test since the 90s, but I can still spot names of compounds that seem like something with a lipid (fatty) tail and a polar head of some sort. If one of the top few ingredients in one of these frilly-named bath products is one of those compounds, then I can use it as soap. I can't read the marketing code, but I can read enough of the chemistry code to find what I'm looking for.
Edit: Conditioners seem to have a lot of fatty alcohols. I don't know why that never threw me off. Maybe because conditioners are labelled "conditioner" so consistently, I got used to it.