Well. Dean talks like he knows everything so forgive him for assuming he ought to trust that authoritative tone. He expects Dean to trust him if this were something more in his realm of expertise, after all.

"I'm- not sure if we should be antagonising our friend. But we should at least find a few more mirrors." And if a few more mirrors are the same then they can decide on their next course of action. Doc leaves the sheet piled on the floor.

"There were a few upstairs. One in each bedroom, and the bathroom of course."