so after finding out about this, i decided to investigate some more. let's take a random product that was in my closet: schwarzkopf gliss kur ultimate oil elixir conditioner. it has thirty ingredients (isn't that, in itself, fact enough...). it boasts about containing oil elixir. oils are generally healthy, i do know that much. the ingredient supplying named oil is argania spinosa kernel oil. that's good: it means that there's pure argan oil in this (but not much: it's the eighth ingredient on the list).
what about the other twenty-nine ingredients? i went through all of them (using mostly the information on this and this website). nine are classified as irritants or worse (or are usually tested on animals - equally bad). and then quite a few lack enough research data to say much about them, have harmful effects on the environment or can only be classified when more information about the source is available. sigh.
so, what's the alternative? it's too simple for most multinational commercial companies to do anything with, i guess. oil. coconut oil, argan oil, you name it. the best hair conditioner you can find.