Does it help if the same guest has charged back stays at other motels?

Your case is decided on your facts, so a pattern elsewhere is never the foundation of a claim. Where it becomes useful is on the narrow question of whether the service complaint was made in good faith. If a guest has told three properties in eighteen months that the room was unusable, and each time only after checking out and completing the stay, that is relevant to whether they genuinely could not use yours. Evidence like that has to arrive in usable form, which means something in writing from the other operator rather than a story you repeat.

There is also a defensive use that owners overlook. Local operators talk, and knowing that a particular name has done this before changes what you do at check-in rather than what you argue afterwards. Capturing a signature, photographing the room condition at handover, and retaining lock logs for that stay costs nothing and converts a probable loss into a documented one. If you belong to a local lodging association, this is the sort of thing worth raising with peers, being careful to stick to facts about transactions rather than characterisations of people.