I once tried to explain to a Principal how obnoxious it was to observe on the day before vacations, especially late in the day. He claimed he needed to observe then, to see who was working. He thought this was the best way to see what a teacher was really about. I couldn't believe I was hearing correctly. A good Principal walks around the building all the time and knows exactly what every teacher in the building does all the time. And, by walking around the building and glancing in rooms, he can see what is going on without walking in and unnerving the educator in the room.
Advice over. The gotcha squad is probably lacing up their sneakers as I type.