Nine out of ten

A certain soap from a big global corporation was in Sweden for decades sold with the slogan "Nine out ten movie stars use [our soap]". I remember seeing ads for it, although the slogan had been in use since the 1930s. I assumed the phrase originated in the US, but could not find any example of it. Which is odd, as the soap in question is American.

Even as a teenager I was occasionally a sarcastic twat/genius, so I joked "Nine movie stars out of ten become clean with [the soap brand in question]".

For some reason I remembered this today.

Stuff is still sold by "movie stars", although it has been partly taken over by personalities and influencers. I wonder how clean they are?

Some movie stars seem more interested in the political racket than selling soap. That can be profitable, it may be equally slippery, but it is much dirtier, so maybe they should go back to the soap industry?