This brand still existed into the 1970’s, advertising under the same name! I assume in the 1940’s, the modern slang was not in common use. Some word origin sites say “poo” arose in the 1950’s. By the 1970’s, this branding must have become problematic!
Nothing wrong with the product, as far as I know. Similar dry shampoos can be purchased today, under rather different branding.
The steam! The benefits of shower steam are lifesaving for us poor congested people who have to live without a sauna.