Clues to look for: Bolt-on wheels. Cheesy steel caliper brakes. Also the presence of no-name components like shifters and such.
Can't say much about the second bike, the guy doesn't give any specs. Send him an e-mail and ask for better pics and what sort of equipment the bike is wearing.
I sell all my re-built bikes on Craigslist; I always list exactly what I've done to them, what the equipment spec is, the frame size, and so forth. I offer to send the high-res picture to anyone making inquiries.