Had a friend who was real big in one martial art or another. Tae Kwon Do, I think. studied under various masters, was a sort of unofficial diplomat for the sport(?). One of her hobbies was to survey the classes at dojo's she'd heard bad things about, go in as the worst student ever, and if the teacher really had no business teaching, reveal it in the most awkward and accidentally on purpose ways she could.
I'm not sure which was faster, her kicks or her ability to help fools hang themselves.