This is one of those "am I crazy?" situations. I cannot get Frame:UnregisterEvent to work. There is no error, but it obviously doesn't have an effect either, since the "unregistered" event continues to be trapped.
Furthermore, Frame:UnregisterAllEvents doesn't seem to exist at all, despite what WoWWiki says.
Am I mistaken in my observations? If so, please correct me! If not, are there workarounds?