I'm not talking about today, I'm talking about back like way back in the day when the "blue rinse" was part of a normal blonde dye job that had to be done by a professional at a salon.

Older ladies back then were likely to have cataracts changing their color perception, so rather than listen to the (usually) young stylist, they left too much blue in. But to them and their peers, it looked the same as when they were young.

I fucked up and put "have" instead of "had".

Not like I'm an expert, but I don't think the literal "blue rinse" has been a thing for a very long time.