I don't see anything that jumps out as scam. I've never seen anyone post a 75k van with elaborate and personal pics that was. I think the big question is the color thing on the rear door sill. Email that question to the seller and they'll know you're paying attention. Their response should be telling of a lot of things.
For some reason I think I remember seeing this van before on some site and the pictures they just sent. My other thought on this based on the current market it seems underpriced. If it was me I would be very careful and would only give a deposit that I would be willing to loose. "Once bitten, twice shy."
The gray you see may just be a protective undercoat spray or gray weather guard membrane that extends the length of the floor to the sill under the rear doors. A good idea I might add seeing that it's an area that's known to rust Especially if your into beach or water sports.
Don't want to change the subject but my van is maroon but as you can see I used a black weather guard membrane over the bare metal floor bed.
Not only does it protect the van bed from water it also seals any protrusions when attaching the plywood subfloor.