Here is what I had in mind. The battle config item_check is now a bit flag type so it can be set to check inventory, cart, or storage. I talked with Lighta and we both agreed guild storage isn't needed since it will end up in an inventory, cart, or storage and be removed from there. Item in storage are cleared out when chrif_save() is ran (on character logout). Rather than adding an itemdb_check() for mail and auction there we can just include another check to when mail and auctions are created to determine if the item is bad or not before inserting the item.
If people agree with the change we can commit it. It's also open to more ideas!