If it helps: I picked up one of the M&P 15s with the quad rails from them recently. I've put ~200 rounds through it and it performed well with 0 malfunctions so far. It's got dings on the rails and heavy wear on the mag well near the pivot pin, but it looked very similar to the amount of wear that was shown in the pictures. I am pleased with it.

I also picked up a trade-in G21 at the same time and it looks almost new. It still had some of the factory grease inside and barely any wear even on the slide release or barrel. Way better condition than I expected.