I cant imagine smells the same way I can imagine a music or an image at all. I remember what something tastes like, but I cant like, think of it and "feel" the taste I have in mind. It stays vague, and only becomes clear when I taste it again.
But you can imagine tastes when dreaming for example. You eat an apple or you touch a wall in a dream, you will often really feel it, even though its not there, so in a way everyone can "imagine tastes"...
Also this is sort of unrelated, but I heard somewhere about another taste that was sort of recently "discovered". You know, like salty, sweet, etc. I dont remember how this taste is called but I remember that the best way to sample it is with parmesan cheese or with anchovies.
Edit: the new taste is called UMAMI. I dont know how NEW it is but yeah.
Edit2 "discovered" isnt really a good term for it. More like, people decided, by some sort of convention, that there was a taste that was too far from being just a combination of those we already knew, and wasnt based on smell either. Try eating parmesan cheese while pinching your nose?