Eyetracks

When you read a new book you get eyetracks all over it. Then it isn't mint any more.

"You look good in that," he said. "Especially wet." I'd noticed the difference. "Feel like an ad for a Broadway parlor. I'll be scraping off eyetracks all night."

"The only good thing in Readerville," said the Lion, "is their library, where they keep copies of science fiction magazines. But all those copies are terribly worn out from being read so much. They have all sorts of unsanitary eyetracks all over them, and the spines are broken because the readers fold their magazines over when they read."