As the New York Times reports in its Business Day section, Trademarks are an important part of branding, and can be key to being found in cyberspace and shelf space. It is important to review existing trademarks, both to support them and to protect them from encroachment from others.
Selection of a trademark is critical. As the Times article points out, a generic phrase may not offer any protection and can cost millions to defend. The marketers of Pretzel Crisps are in a battle with Frito-Lay, an opponent with very deep pockets.
Having been involved in a number of trademark disputes, I know first hand that it is better to avoid them, then to take the chance. Even where a questionable mark gets past the Trademark office, competitors may take a dim view of what has been filed. In the Pretzel Crisps case, a cancellation proceeding is pending to eliminate any trademark protection for the name. If successful, Frito-Lay and others would be free to market their own Pretzel Crisps.