Craigslist.. isn't very reliable. What you experience is worth its weight in gold. Like waresbear suggests.. go down there (like you are.. yay!) experience a lesson, see if you like HER, how she teaches.. how her students look.. are they using their seat properly, are they communicating effectively with their horses, are they getting better as time goes by, are questions being asked and answered, is the instructor paying attention to the student and horse or to others, etc. Ask everything.. question everything. Make a list of what you want to feel at the end of a lesson (accomplished, sore, happy, determined, tired, etc.) and see if that is what the students are emulating or if they are more angry or crying or whatnot.
Ask around too.. find someone that rocks riding their horse and ask them if they can recommend a trainer.
"Strength is the ability to use a muscle without tension"