i always tap tone wood, just to see if i can hear the difference between other/or the same wood/s that are of the same size. however, i don't make judgement like: 'wow, this piece of wood [just say it is pine, but i don't know that] sounds very resonant, perhaps i should make a guitar with it.' i think tone tapping is not by any means a surefire method of judging the tonal properties of wood. it is just a way of experimenting or exploring the wonders of tonality in woods.
it is kind of like trying to draw a perfect circle free hand. it is impossible to draw a perfect circle free hand. and if you have drawn a circle, it may look perfect to the naked eye, until you put a circular object of the same diameter of that circle and discover it is not perfect at all. so the circle may look perfect, but it is not. just like making a judgement with the tone tapping method, you think the tone of that wood sounds high or low or sustains a lot, you could be wrong. the only way you are going to draw a perfect circle is with a circular object or a compass, and the only way you are going to have the best judgement of wood tones is if you put strings on the wood. but after all, trying to draw a perfect circle free hand is just an experiment, just like tone tapping.