Harold ... at some point, one has to apply "common sense," consider the context, make their call, and be prepared to persuade a dozen strangers to agree with them.
West of Chicago, an "adult" bookstore converted part of their store to a place where one could watch the films. The store said it was just a 'viewing room,' thus exempt from movie theater requirements. The AHJ replied that the room had 25 seats, the seats were on an inclined base, the screen was 12 ft. high .... as far as he was concerned, it was a theater. Litigation began, but the store owner had to conceed that it sure looked like a theater! Issue resolved.
The same issue arose in one home, were the 'flipper' was trying to present a garage conversion as an additional bedroom. The only problem was, that in order to get from the kitchen to either the patio, or the detached new garage, one had to pass through the converted garage. Pretty hard for that to be a bedroom (Though I was raised with such an arrangement for a few years!)
Again, when visiting my Grandmother, I was usually 'put up' in the room that had originally been a porch. With just enough room for a bed and a space heater, this completely enclosed space was a 'room' in every sense of the word. Later, it was filled with shelving, and you could honestly say it was a 'pantry.'
That's why I placed the stress on 'habitable' space. Closets, pantries, mud rooms, etc. do not need to meet the same requirements are actual 'living' space. You really need to take things in context.
Customer cleverness aside, it does seem that architects delight in designing spaces that blur distinctions. Article 90.1 aside, the NEC is most certainly being used as a 'design manual,' and even the most exclusive properties are built to 'code minimums.' At some point, the market has to kick in, and reign in these excesses.
Like the experience of that 'flipper,' who listed that house as having three bedrooms. Viewers who really wanted three bedrooms walked away in disgust; whatever that room was, none could imagine sleeping there!
