Not a very serious post but you said..

How about lumps of grunge on a chip. Such grunge was not aquired by normal use (sliding of chips over a felt/felt like surface).

In college our fraternity house had a couple poker nights a week. There was one clown with a nose problem. He sneezed constantly and never had a snot rag. He often blew boogers all over the chips and felt. We finally had to buy new felt and wash all the chips. At that point he couldn't come to the TKE house anymore.

We thought it was pretty funny back then.

Mark