Really it should be a manufacture requirement that the barrel port on the device have a waterproof hard to destroy sticker, or case moulding that lists it's requirements. As the years have gone by I've seen way too many devices with a plug hole and no idea what it thirsts for, leading to deep searches on the net for the product. Also the wall warts themselves are commonly made by some other group, so once separated there is little to no visible pairing identification other than looking for output/input power on both devices.