Word-of-mouth isn't the solution to every marketing problem, however. Speed is perhaps its biggest limitation. Compared to other marketing tools, word-of-mouth takes a long time to work. If you want to reach the whole nation really fast, says Cafferky, this isn't the answer.
Quite a while may go by before even a highly effective word-of-mouth campaign begins to bear major fruit. Anderson says entrepreneurs can generate half their new business from word-of-mouth in three years, all of it within five years. "It will help before five years," he says, "but it won't provide a total source of new jobs."
Word-of-mouth also offers very limited control. "When you buy an ad in the newspaper, you can control exactly what is said, when it is said and, to some degree, to whom it is said," says Cafferky. "But the fact is, you just cannot control what and when a consumer says something about your product."
And if your marketing goal is to point out a competitor's faults, word-of-mouth will be of little use. "You can't be negative with it against a competitor," says Davies. "You need to stay positive."
Finally, word-of-mouth is likely to be of limited value in some industries and with some products simply because they're not frequent topics of conversation. "When was the last time somebody told you about some great shoestrings they bought?" asks Wilson. "The mundane things people buy, we don't talk about."