This note from the Tooth Fairy should serve as a savage reminder that you need to keep your room clean. I can't imagine how humiliated this kid must have felt knowing that a magical creature entered their room and was so disgusted by it that she couldn't help but be petty about it. I'd be traumatized if I were that kid. If your parent says your room is a filthy mess, you roll your eyes. If a fairy tells you that, you believe it.
This will come to bite the parents in the ass once the kid finds out that the tooth fairy isn't real. That's why you can't build these types of lessons off of lies. Once the first lie is destroyed, the whole foundation is destroyed. This kid won't keep their room clean for the rest of their lives knowing that there's no longer some judgemental fairy looking over their shoulder.