He grinned a bit, his nose and mouth working almost comically to try and keep the dust out of his face.
"It's a sound plan," he said with a nod, reaching up to rub his nose and smearing a bit of dirt on it in the process - he was really not used to cleaning the Muggle way - "A lot of the students here almost need to be tricked," he said with a small grin.
He continued to move the rag in circles, but he was pretty sure all it was really doing was spreading the dust around. His eyes trailed back over to where she was, to confirm that he was, in fact, doing this correctly.