"So?" he inquires, amused. "A sufficiently skillful speaker can say whatever he wants using only the truth. And it's your own demeanor that made everyone suspect the cheering charms."
"I do," he nods. "Especially in one that didn't try to make her feel like a monster for not hating one or the others of her former masters. It's different for the school elves; they've been raised and trained to serve the school and taught to have pride in its reputation. She wouldn't have been taught that pride, and to go from being one elf taking care of her own house to one small piece of a team servicing thousands... you can see how it would feel like a humiliating demotion. And then there's the issue of students leaving every year never to return. Think how that must seem to a family elf. Lodgers are different; they're long-term guests; but for one-seventh of the children to run away every year--that would reflect badly on everyone involved, and they're not exactly logical creatures."