For items that a large institution of the gov't sort are "excessing", it's mostly like what bd139 said. Stuff immediately gets handled based on what path it takes in the disposal process. Furniture goes one way. Office machinery and computers another. Paper gets shredded. There is potential liability associated with selling some things like probes and interconnects, so they get binned along with other wires of any sort. Electronic/scientific equipment goes through a final inspector, who determines a) if there's a storage device inside and removes and destroys it if there is, and b) if an item is on an inter-agency loan pool list, it gets routed to a warehouse where it sits for 90 days or more so that other institutions can use or obtain it. (Universities who work with DOD/DOE get a lot of their high-end stuff this way). Everything else gets handed to some company (a materials handler) they've contracted with to remove it from the site and sell it, either in local auctions or in some cases it goes straight to eBay. They get paid to pick it up, and keep a percentage of the final sales prices for their service.
So unless they've been attached to the unit, things like cables, probes, manuals, etc will always get separated from their respective piece. I can buy cords and probes. But I have to buy a huge container with a ton or more of all sorts of wire to get them. The scrap dealers make their living dealing with this stuff and pay dearly for it.
It's a sad but true story.