Scott has written a great article on what to be wary off with instructors. Regardless of your experience level, this is a MUST READ for all wanting to learn how to breath underwater, better yet for those who currently do and take continuing education classes. Thanks for writing this up Scott, I'm sure it was very painful at times to relive this experience in writing it.

Tragedy at the Breakwater: A checkout dive goes wrong | Scuba diving and skin diving California and beyond