If we are able to taste a "fake" flavor in a way as "rich" as we deem a real taste, we could ask what is the difference? As far as our sensorial system is concerned, it's definitely taste. So, it is reasonable to say it is real in the experiential sense.
What distinguishes a "real" taste and a "simulated taste"? From the perspective outlined above, one answer is how "rich" the experience is (to our senses). Thus, an initial approach to identify virtuality (or "artificiality") is to identify how
"simplified" an experience is compared to an understanding of its "real" counterpart (where "real" here just means "richer" in regard to stimuli).
If an experience is "rich enough" to our senses, a priori, we are unable to distinguish "virtual" from "real" unless, perhaps, through sophisticated maneuvers (eg. clever reasoning, clever observations -- science). In fact, our inclination is to say "it felt so real", which puts the idea of "reality" itself into question [again].
But of course, "virtual worlds" of today do not offer such "richness". Wearing glasses and playing a game is real in the sense that we are living an experience of playing, and we are stimulated by the the instruments of the game (display, sounds, tactile facilities). However they still fall short both in its ability to "fool" ourselves and to be fully capable of supporting a life such as ours within its environment.
Even if we put aside ontological questions, as until now, there are important points to consider (whether we are in a "real universe" or fooled in a "virtual universe"), like the hard problems of identifying life and intelligence -- and how "hurting" a character whose behavior is "artificial" different, karmically, from hurting an actual living being?
Voluntary imagination and dreams, on the other hand, may be different enough to introduce some subtleties.
In terms of [early] buddhist doctrine, I understand that whether the experience is, in essence, virtual or real is insignificant. The point is that we find ourselves in an environment ( a realm of existence, virtual or real) where there is contact through sense bases (irrespective of the "substantial reality" of external objects) and volition (or, to answer fully, paṭiccasamuppāda).
Finally, I seem to recall a sutta where the Buddha might have said something like "there is nothing beyond the sense bases". But I'm very unsure about this, even the actual wording and meaning. Then, there is the question of how supramundane experiences are sensed, and Nibbana itself -- if that makes sense --, which I'm not comfortable to elaborate.