One question I often ask students/pilots is "Can I stall if I am diving vertically towards the ground?" (with model a/c in hand pointing vertically down!) The answers are quite illuminating since almost exclusively all their stalling training has been done from more or less level flight and/or modest bank angles.
Exactly. It's not a point that is really driven home and it's one of the most important things to understand in flying. I suppose time and the syllabus are against most instructors. I don't come entirely virginal to the theory of it, before my whole 250 hrs as a powered pilot I spent 20 odd years as a glider pilot and was an instructor in theory of flight at a military establishment for four years. I already had the background when I started powered so any gaps were I suppose unconsciously filled in by me.