It's easy, do you need to condemn someone? So you cast the thumbs down spell. or maybe you need to heal someone? then you can cast the spell of "ok, you're fine, it's not even a scratch"......
well it also serves to scratch your back.....although maybe the school of magic and sorcery doesn't like this use......well...the face chose you, right?... You're supposed to do whatever you want with it...