The July 27 1932 edition of the Toronto Daily Star contained an ad for Lux Toilet Soap, in which actresses of three different ages claimed that they used it regularly.
I looked up all three of the actresses in Wikipedia, and it appears – as I guess was common in Hollywood – that they (or their studios) were fibbing a bit about their ages.
Helen Chandler (1906-1965) was actually 26, not 20. She had just become famous for starring in Dracula in 1931. Sadly, she began to battle alcoholism in the late 1930s, and she died young while undergoing surgery for a stomach ulcer.
Gertrude Astor (1887-1977) was actually 44, not 30! She appeared in her first movie in 1917, and appeared in many Laurel and Hardy films. She died on her 90th birthday.
Frances Starr (1886-1973) was 46 at the time of this photo, not 39. She appeared in only three movies in the 1930s, but got some work on television in the early 1950s.
Given the inaccuracy of their spokespersons’ ages, I am not entirely convinced that 686 out of 694 important Hollywood actresses depended on Lux Toilet Soap.