Yeah, I have some strict requirements for what I expect in a CFI and a school, since it's my money, time, and my life on the line:
1. Non-smoker.
2. Not be on your phone the entire time while we're in the air (this happened to me previously).
3. Not be some bitter ass person who never got in the airlines or someone bitter because they keep trying and can't get in (I'm never interested in hearing someone complain without being paid for it. Can you tell I work in sales?).
4. Be able to communicate clearly in English, ESL is fine, but not severely broken either, I deal with that at work in Tech, I get paid to do it, I am not paying to deal with it.
5. CFI not smell like an unwiped ass or come in smelling like the night before.
6. CFI must respect my decision not to fly a certain plane if I don't believe it's safe for flight (bad experience with this too, long story that includes left side brake locking up on my landing, the seat lock failing{wheeeee?!}, and engine nearly running out of oil due to a leak, I can elaborate if you want).
7. The planes must be well kept and have all maintenance logs available for me to inspect
8. The schedule be consistent and not change at the last minute every single time (also from experience)
Background on me is I've started and stopped flight training throughout life due to, well, life. Early years I trained to be an A&P but decided I didn't want to always live in a studio apartment eating pork and beans each night because people don't pay mechanics, but I've rebuilt more engines than I care to remember for myself and others, presently rebuilding my N55 for my BMW. Considering the engine is what is keeping us flying and allows for the most controlled method to land safely, I hold it's maintenance and functional operation in high regards, so I want to avoid things like pencil whipped annuals because lives are at risk here, we can't just pull over.