Something like how to wash your hair can seem so simple—and yet, so many people get it wrong. From the type of shampoo they use, to the amount, to the frequency… It’s much more involved than “wash, ...

Describing a shampoo as “cult” is like describing a laundry start-up as “revolutionary,” or a Katy Perry outfit as “iconic.” The adjective mocks its own premise. I understand this. But I am going to ...