You reflected the example wrong though. Asking "How many blue cats are bouncing?" makes the presupposition that blue cats exist. "How many bottles of milk are in the fridge?" makes no presupposition of any kind. To demonstrate my point using your example: You ask: "How many of the milk bottles in the fridge are rancid?" I go to the fridge and see that there is no milk in the fridge. I now can't answer with any number at all, not even zero. Because if I say "None!" or "Zero!" then I will just have said: "I confirm that there is milk in the fridge, and state that none of it is rancid." which contradicts what I have just learned to be the truth.

This is not po-tay-to po-tah-to, people. It's a real thing.