I know many guitar instructors in the area and I can't honestly say any of them are "bad." Some instructors studied with me and I know that their method doesn't stray far from my own.
A one-on-one relationship such as that of private guitar instructor and student is much like any relationship we have in school, at work or in our social circles. Some folks just "click," others struggle to get along.
I have inherited students from other instructors, and I have no doubt just the opposite is true. I do everything I can to relate to each student, constantly striving to establish common ground and connect. I truly care about the well being of each student so far as studying with me goes.
My advice is to meet with your or your child's instructor for a test lesson. Do not accept anyone who comes off as condescendin or bossy, as those traits will be amplified over time.
Look into your instructor's background. What has he done professionally? How long has he been teaching?
I have nothing bad to say about on-line methods, but the students most likely to benefit from that type of study should be well beyond the basics. An on-line instructor can't assess whether the student is getting any particular concept and he certainly can't reach out and move a student's finger into the correct position.
All things said, everybody is different and you should be prepared to look into a variety of teachers and methods before making a decision.