You can't really trust anything they give you (they could have copied and pasted it from something interesting that they Googled, or for that matter any open-so

You can't really trust anything they give you (they could have copied and pasted it from something interesting that they Googled, or for that matter any open-source project), so you have to judge code in person. And you can't, because a whiteboard is not a place to write code. Instead, ask them to describe their accomplishments in detail, including the approaches they took to achieve those things. Ask them how they would solve some hypothetical problems that you pose. This kind of discussion can't really be faked, and tells you immediately what kind of thinker they are.