Junk Wax

From BaseballCardPedia.com

Junk Wax: A derogatory phrase commonly used to describe boxes or packs of cards that have little monetary value. These boxes and packs are usually from the mid-1980s to the late 1990s, a time when card manufacturers overproduced cards. Finding junk wax for sale at garage sales, flea markets and online auction sites is quite common.

The term can also include boxes or packs of cards produced outside this time frame that, for various other reasons (quality, popularity, cost, etc...), also have little monetary value.