Returns are in whatever shape they were when they received them with the exception being that they fixed the specific issue that it came in for. I've seen them at their best and worst.
I have gotten returns that looked like new, and ones that literally looked like they fell out of the Airllane without a parachute.
I got an iMac with a dead Ethernet port, mouse that was coarse and rough like it'd been dragged down the freeway, the computer had a 2 inch chip in the case (literally missing a chunk), and the screen had thick scrapes gouged in from one corner to the other like a knife scrape (though not as precise), and a keyboard that looked only marginally better than the mouse.
Called apple, their answer was although it came that way, that their warranty doesn't cover cosmetic damage. They agreed only to replace the main board due to the dead Ethernet port.
No damage to its shipping container. All packaging intact and perfect. It left apple like that. But even though it had only been signed for 5 minutes prior, apple said no to repairing the cosmetic damage that it shipped from them with.
Computer shop had it within 20 minutes of coming out of the box.
Privately owned shop was kind, and managed to shuffle some paperwork and got the damaged parts replaced. By the time they were done, I think the cd rom and hard drive were only parts retained.
If it hadn't been for a private shop, I'd have been stuck with the knarliest looking $2000 computer ever.
Expect that all Apple has done is repaired the issue it came to them for. Nothing else.
That said, generally refurbs have been good. But it will be in whatever physical condition they received it in.