Interestingly, if the natural process of a product name becoming a part of the english language that wuukiee mentions above goes far enough, the company being misnomer'd can actually lose the copyright/trademark in question once the government becomes satisfied that the trademarked name has become a word.
(I believe this at one time happened to the Otis Elevator company over the word "Elevator"; however, i was unable to find confirmation of this, and Elevator may have never been legitimately trademarked in the first place. However, while looking for confirmation i did find the page http://www.roundsmiller.com/stealin'.htm , which has some rather interesting discussion on the subject. Search for the "WHY TRADEMARKS ARE VALUABLE?" section.)
According to that page, trademarks that have been invalidated because they became part of the vernacular
(The Otis Elevator
), and Asprin
Company). As a result any
competing company can now sell products under those three names, and the original name owners have no valid claim whatsoever against this.