Line extensions are tempting for companies as a way to leverage an existing popular brand. However, if the brand name has become near generic so that consumers consider the name and the product to be one and the same, Ries and Trout generally do not believe that a line extension is a good idea.
Consider the case of Life Savers candy. To consumers, the brand name is synonymous with the hard round candy that has a hole in the middle. Nonetheless, the company introduced a Life Savers chewing gum. This use of the Life Savers name was not consistent with the consumer’s view of it, and the Life Savers chewing gum brand failed. The company later introduced the first brand of soft bubble gum and gave it a new name: Bubble Yum. This product was very successful because it not only had a name different from the hard candy, it also had the the advantage of being the first soft bubble gum.
Ries and Trout cite many examples of failures due to line extensions. The consistent pattern in these cases is that either the new product does not succeed, or the original successful product loses market share as a result of its position being weakened by a diluted brand name.