Copyblogger has some great quotes from Mark Twain that he thinks apply to bloggers. They could also be applied to writing for advertising and promotions. Too often I see good design spoiled by mediocre writing. The Mark Twain Guide to Better Blogging | Copyblogger

"The difference between the right word and almost right word is the difference between lightning and a lightning bug."

All of the elements of a design project need to me held to the same level of scrutiny. None can be overlooked. A poor choice of words will ruin a promotional piece just as fast as a poor design.