The Orphan Check Tool performs checks on your eBay listings, reporting and fixing some issues. Run it periodically to check for issues.
The tool will check for items listed on eBay that are also in your Zen Cart store, but not associated with each other. It will fix these links so that the two stores stay in sync. It matches the products using the Zen Cart product ID which the plug-in stores as a hidden attribute in the eBay listing when it is created.
The tool also disassociates Zen Cart store products from eBay listings that have ended so that there won't be an issue if the plug-in tries to relist the product on eBay.
The tool displays messages reporting products that are listed on eBay without a hidden product ID attribute. These will usually be listings you added yourself rather than through the plug-in.
The tool will also display messages reporting products that are listed on eBay with a hidden product ID attribute, but the product doesn't exist in your Zen Cart store. Most likely the Zen Cart store product was deleted after the eBay listing was created. You should review the eBay listing and delete it if the product is no longer available.