PURE for a chemical is found to be so highly descriptive it is denied a trademark registration. Because the wrong type of term for a trademark was chosen, because a skilled trademark attorney was not consulted when the term was chosen, or because the trademark owner allowed the term to fall into the public domain. Terms that have direct meaning in relation to goods or services have to remain available for all those in your industry to use to describe their goods or services. Merely misspelling a term may not avoid descriptiveness.
Arbitrary marks are stronger still than suggestive marks.
Made up terms with no meaning in any language are the strongest trademarks. Of course, advertising personnel often prefer marks that have some descriptive meaning to convey an idea of the product's attributes to consumers. Your trademark attorney prefers marks that are suggestive, arbitrary or made-up terms, rather than descriptive terms. There are, however, ways to accomplish the advertiser's goal without sacrificing trademark strength. Combine two highly suggestive components into one mark.