WHAT'S IN A NAME? As Arlene is about to guess the product of Ed Dempsey, the aspirin manufacturer, she asks, "Can we use a brand name?" She showed concern because the broadcast media treated the use of brand names in unauthorized settings very carefully from its earliest days in the 1920s until the 1990s when cautions were relaxed. While "aspirin" was a name in the public domain in 1964, it had not always been so. The Bayer company created the name Aspirin and registered it as a trademark in the late 1800's, but within 20 years, the name was in common use and a federal court ruled in 1921 that the trademark owner no longer had a claim to the name. Since then, other owners of common trade names have exerted concerted efforts to keep their names out of the public domain.
Common trademarks often incorrectly used as generic terms include Band-Aid, Dumpster, Jell-O, Kleenex, Scotch tape and Xerox. Those names are still registered as trademarks.
Common trademarked names which are struggling to retain their trademarked status include Ace bandage, Advil, Ajax, Aqua-Lung, Baggies, Beer Nuts, BVDs, ChapStick, Crescent wrench, Freon, Hells Angels, Hula Hoop, Kitty Litter, Ouija game board, Pampers, Ping-Pong, Port-a-Potty, Weedeater, Windex, Ziplock and more.
The list of formerly copyrighted names that have entered the public domain, much to their owners' regret, is surprisingly long and includes Allen wrench, bikini, cellophane, crock pot, dry ice, escalator, gramophone, granola, heroin (trademarked by Bayer as a pain reliever!), lanolin, laundromat, mimeograph, plasterboard, yo-yo and zipper.
For more reading: http://en.wikipedia.org/wiki/List_of_generic_and_genericized_trademarks
Lee McIntyre (2006)