Yes, we had this discussion several months ago.  Someone suggested
that when unsolicited books arrive you just keep them and writ F&G a
letter thanking them for the donation to your library.  I did this and they
sent someone to pick it up, so we didn't have to pay postage.  I have
explained the situation to many people at F&G including the fact that this
information is now in the hands of over a thousand medlibbers.  They
always say they will take it up with their manager.