We run a video games database at altarofgaming.com (trying to become the IMDB of video games).
We keep every unique copy of each game for our archive, uploading scans of the artwork, screenshots, videos and as much information as we can about each game.
We resell all duplicates through our eBay store. Each item's condition is clearly marked on the title (for example missing game discs, manuals etc.), clear pictures are taken for each item, and if any further information is required it's added on the item's description.
If a game is tested, it's clearly marked on the title, and pictures are included showing it work. We don't test cheaper games as it takes too much time, but having handled over 50,000 physical games, we know the types of disc damage that affects gameplay, and are always careful to not list games that are not working (unless stated in the title).
Thanks for checking out our eBay storefront, feel free to ask any questions, or get in touch to sell your old games!