Above The Law makes it a practice this time of year to post about the bad things law professors do concerning exams, including reusing old exams, recycling practice exam questions, leaking an exam on a list serve, taking multiple choice questions directly from a commercial study guide (okay, that's a Volokh Conspiracy nugget), and, most recently, sending the exam and all the answers instead of the instructions for taking it.
My favorite comment on the subject was in response to the Volokh Conspiracy post on reusing law school questions:
The advantage of teaching taxation is that you can use the same questions every year, but Congress will change the answers for you.