Since you are going to be spending several thousand dollars to learn to fly, you have every right to expect your CFI to be a professional. He will help you obtain your best performance on the practical test. Before you commit yourself, look around. If you have a pilot friend, get him or her to look around with you. Play the tourist ask questions satisfy yourself.
Most flight schools have some kind of demonstration flight, usually at a reduced rate.
I m not sure they are good evaluation tools for prospective students. Get a preflight briefing, an inflight lesson, and a postflight critique find out how your prospective CFI teaches the four fundamentals of flight. If you were to come to me for your first flight lesson, well, as long as you can walk and chew gum at the same time, then you will do everything except land the plane the first time out. This includes preflight, engine startup, using the radio, taxi, runup, takeoff, and so on. Do not forget that throughout your training course.