It seems like most of these coding interviews, actually belong in a college classroom.

So my question is simple - Are these style of interviews, where you are asked contrived logic questions, recursive graph searches, random array tricks, etc... Effective means of assessing a candidates potential for success at your company?

I just have a hard time subscribing to the notion that these coding challenges, are more indicative of a candidates potential for success, than their resume, and personal demeanor would indicate.