This is after Harry has seen the Mirror of Erised for the third time, and he finds Professor Dumbledore sitting in the same room.
My comment --> 
Harry stood up.
"Sir -- Professor Dumbledore? Can I ask you something?" [Hahahaha! I love it when someone asks this question. ;)]
"Obviously, you've just done so," Dumbledore smiled. "You may ask me one more thing, however."
"What do you see when you look in the mirror?"
"I? I see myself holding a pair of thick, woolen socks."
"One can never have enough socks, " said Dumbledore. "Another Christmas has come and gone and I didn't get a single pair. People will insist on giving me books."
So Dumbledore desperately desires thick, woolen socks.
My question is: Was Dumbledore not truthful when he answered this question like Harry thought or this clue has been answered in the later books? I couldn't put together the pieces of this puzzle.