Well, with the outset of only one beverage served "wants both coffee and tea" would never really be satisifed, if taken literally. But Sam said "I had a 66% chance of giving them something they wanted". Something they wanted also means partially fulfillment of a result. If you want tea and coffee, tea is in that. In that sense doing both would mean 100% satisfaction in all cases. Even if you only would want one, you can of course skip the other beverage, but that means more effort to get there.
If you take into account the result of the experiment will only be one beverage, I would interpret the question as a validity expression.
Is tea "tea or coffee": Yes
Is coffee "tea or coffee": Yes
Both drinks satisfy the answer "Yes" to the question "Do you want tea or coffee", 100% fulfillment.
Seeing it that way, my father is not withholding more specifications needed to serve him, what he will accept. So if the answer would be "no", no beverage would be the correct response, if the answer is "yes", any beverage is the correct response. Defining four results means you "accuse" my father of (impolitly) withholding informations/specifications.
Taking it to the context of IT project specifications, if I see specifications like that I most often ask for a better specification of customer demands, I sometimes try to not annoy and instead make assumptions I may or may not present as suggestion or recommendation and in the other case take as granted. Rarely, with customers I can do without I would implement the minimum and then let them either be satisfied or risc them leaving unsatisfied.
If you ever took part in a public tender you'd know how annoying it also can be to have very detailed specifications...Realistically there is a break even point for a good specification outlining the necessary solution and still staying assessible and not too long.
Getting towards total satisfaction the agile approach via iterations can save time on both ends, even if you implement something you need to scrap. You'll only stand out as a bad vendor or supplier, if you tend to only do minimum work and show no intererst to understand the gist of the needs and you're surely out, if you even fail to go at least in the right direction towards the goal. It's always easier to talk about the wanted solution when talking about partial solutions. In that sense my father could ask for the other beverage, if he really would want both and got one.
Back on topic of the real tea or coffee question of my mother, my father mostly meant to let my mother have the choice, obviously, besides to tease. Sometimes she wanted him to make the choice, but most important to state, perhaps: They are still married.
Bye, Olaf.