So don't give that sort of interview; give one you wouldn't walk out of where, if it goes well, you'll be able to write a compelling argument about why the candidate should work at Google, and if it doesn't go well you'll be able to write about where the gaps are.

Feel free to ping me on IM (username is in my profile) if you'd like to talk about how to do this in a way that helps hiring committee make informed decisions.