I agree with Ellen. I've been dancing Pro/Am off and on for 10 years and I've always ended up working with teachers who had very few pro/am students, and also competed professionally and coached amateur couples. My teachers have always been deadicated to teaching dance, no matter if it's to wedding couples, kids, adults, or pro/am ladies. I've been fortuante that way -- but the truth is that in this matter we make our own luck. A good, focussed, interested, deadicated student who knows why she is dancing paired with a caring teacher who sees himself as a mentor is a good combination that will produce some nice dancing and lots of satisfaction in both teacher and student. What teacher doesn't like to teach an enthusiastic student who really listens to them, takes in the lessons be the mental or technique or whatever, and constantly grows and improves as a dancer?
If someone is having problems with a teacher, the best advice is to shop around and find another teacher. And keep sharing advice here as to what makes for a good teacher and a good student.