The term "wow factor" was originally used to describe the design of new buildings and the term has been in use since the 1990s. The "wow factor" is defined as "a quality that makes someone feel excited or surprised when they first see something, e.g., The entrance will be rebuilt to create more of a wow factor. The wow factor is also something (a factor) that excites or stimulates the viewer's/person's sense of sight, smell, touch, hearing or taste. It is possible for something to impress people with more than one wow factor, therefore the term is countable. This answer may or may not have had any wow factors... :)

In both instances, "wow factor" is more of an adjective than a true noun. Both phrases are legitimate uses of "wow factor". However, as to the food reference, it is referring to a taste enhancement that "wows" the senses. When you refer to the singer, you are talking about the "wow factor" more as a replacement or slang for a word like charisma or a phrase like "stage presence". Hope you find that useful, if you have other questions, feel free to contact me for a session and we can discuss it.