I would definitely recommend providing a response, but in most states you are not required to unless before a court. If they are only questioning a few items it is most likely a honest concern and not someone trying to scam you. Ignoring it also makes them more apt to be spiteful and file for damages.
I require all tenants to send a detailed list of what deposit items they believe are incorrect and why before reviewing. That helps to set the baseline around what you need to review and prevents the time wasting in justifying every charge. I would start by providing a copy of the condition catalog and a photo of the returned product. It sounds like the example charge was warranted and hopefully a few photos will be enough to make them wake away. At this stage I send the bare minimum to justify the charges. I wouldn't bother send before photos or any receipts unless the condition catalog doesn't outline something or it would easily shut down the argument.
I self manage and try to do extra work upfront with deposits in case these questions come up. I'd rather have everything justified in advance to help save time in these situations and cover myself should anything go to court. I'm include a copy of my latest backup from a deposit I'm sending out tomorrow. https://docs.google.com/docume...