Isn't worth a bean

A colloquial saying meaning "worthless".
It cannot be used in reverse i.e. "is worth a bean" because a "bean" is thought to be worthless, and not be worth a bean is to less that worthless, so to be "worth a bean" has such a broad meaning it is indeed meaningless.

"Chamillionaire's album isn't worth a bean"

by A speaker's curtain November 6, 2006