Don't buy it. Tone quality especially is too subjective, too undefined, too inexact a science to make any promises to please. Having taught and having observed many different piano teachers and their students for so many years, I have to say that I no longer know how to answer this question. Music is such a big field. Every teacher is different.
Every student is different.
It's pretty much a matter of finding a match that works. I guess you should just try a teacher out. Piano lessons are really adventures in psychology. If the student becomes engaged, then everything is wonderful. Being engaged and on-task is what learning is all about.