As a kid, we all mostly fear what is underneath our beds. Instead of fearing Monsters underneath your bed or lingering in your wardrobes, these monsters have jobs to do, and that is to clean the child's bedroom. They are friendly monsters with unique features that help them get their job done.
They are a splash of colour that brings joy and happiness to the young boy in the book. The book can bring comfort and hopefully reassure them if they hear any strange monsters in the bed, they know it will be the friendly monsters. This can help children not to fear monsters, and instead, we imagine them as our friends.