Was there a specific attack vector you commonly saw from candidates in interviews? It would seem pretty difficult to fake having built a real product or made significant open source contributions. In fact would probably be as difficult or more difficult than faking having written a book, and as far as I know book publishers aren't constantly trying to weed out would-be authors who have faked their previous publications.

I'm not saying you're wrong, especially since we hear about this kind of thing all the time, but I just don't see anything about coding that would seem to make it uniquely conducive to this sort of deception.