This vintage beauty advertisement is advertising a hair product. But would this shampoo really give you the "most beautiful hair in the world"? Advertisements like this make me very skeptical of advertising in general. There is no way to truly know whether this would give someone the most beautiful hair in the world.
The advertisement also states that "4 our of 5 top hollywood stars" use the product. These "hollywood stars" are supposedly people we admire, and this is supposed to want to use the product because these admired people also use it. This shows ethos, because it establishes a common ground or common liking in the audience.
These two statements have no way of being proved true, and are also very unlikely. These broad statements could also have different meanings to different people. The most "beautiful hair in the world" could be interpreted in different ways. For example,one person may think curly hair is the most beautiful, while another may think straight is the most beautiful. Either way, there is still no way to prove either one of these statements in the advertisements.