"I'm not currently teaching anone anything by any sort of example," Adam said, flipping the book back open and going back to reading. "I am doing research at quite an early hour. And stains are incidental - any wizard worth his wand should have no problem removing them. In the event there would be a stain, which I assure you is quite as likely to happen in any other part of the castle as this one."
"I am not, however, certain what your point about being affected by dark spells is," Adam continued. "Since I, too, seem to have been affected by such. Shall I give up reading anything at all and not contribute to figuring out what the hell is wong with me?"