I have had both good and bad teachers in the public schools.  The bad ones gave off the air of I-really-don't-want-to-be-here all too often.  Those classes had high skip rates, bored kids, etc.. The slightest involvement in your child's life can alert you to whether a school is doing well.  

And frankly, the non profit/for profit argument is easy to look at.

In a for profit environment, the reputation of the school is going to matter most. It affects the pocketbook. A better selection and real motivation to provide a better product through competition gives a strong incentive to have the best educators for the money, and monitor them appropriately.   Bottom line says teachers who suck are fired.