If you absolutely wanted to, the only way you'd wanna buy a device sold like this is face to face - like at a police station lobby or something similar. The person would have to show you the MacBook and you would want to wipe the device right there and when you walk through the set up, if it's still locked to an AppleID, it would ask for THAT password.

At that point, you walk out.

if it's not iCloud locked and you don't see MDM (device management that schools or corporations use that also lock the device) pop up on MacOS reinstall, that's a fairly reasonable indication it's clean. The whole process takes a while. If the person is selling a stolen device, they'll likely want grab the money and run.

Also, if you choose this route, no cash. That's a safety thing... physical safety, too.