Proven Quality? There was no national standards that certified these things, but these assertions are commonplace. Everyone expected them. Garrott was a high-line chocolate, packed in fancy gift-boxes for those special occasions. A 1938 account of their early sales practices can be found here, and we learn that Garrott had some interesting candy bar names:

Cave Man

Jazz-O

Vampire

Narcissus

The Puff Box