Taste
Taste is probably the least useful communication channel available to advertising. Like touch, taste requires the potential customer to come in actual physical contact with the product. However, taste is even more limited than touch. There are few products other than food for which taste is a major selling point, and there is virtually no medium in which an ad can be placed that people are likely to lick; I'm sure few people are going to lick a magazine page or the TV screen, nor get much sense of what the product tastes like from them. It is possible to use direct mail, sending samples to homes, but that is an expensive way to advertise.
Thus, taste is much more effective in personal selling, such as sampling foods in supermarkets or in door-to-door sales.
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The remaining two senses, sound and sight, are the most effective and easily used channels of communication available to advertising. For these reasons virtually all advertising relies on them.