Such exaggerations have been so common that the public takes them with a grain of salt and partly excuses them as being due to the advertiser's license of self-assertiveness. Nevertheless, the fact remains that superlative generalities are weak arguments and far less convincing than a statement of facts. Much advertising copy would be improved immensely by doing away with brag and substituting actual facts about the merits of the article.
Principles of Advertising, 1923, p. 439.