This happened to me lots of times:
The candidate arrives for the interview. We spend a few minutes for the introductions and small talk. Then, the first question: “What is a class and what is an object?”… <crickets>…
At this moment I normally try a few other questions, just to be polite, but my mind is made up: I just wasted my time!
It can be even worse – I get an answer that is sufficiently vague and uses some buzzwords to be considered correct. So I spend let’s say 30 minutes trying to determine if the candidate knows stuff and has a problem expressing himself or he’s just taking long shots with his answers.
And then, the practical part: get him or her to write some simple code - a class with a property and a method (C#). As a programmer you probably write dozens of those each day. And that’s when I have my confirmation: the candidate doesn’t even know the syntax for a property or a method. He’s looking for the door, thinking if it would be less shameful if he just got up and ran. And I just wasted even more of my time!
Now, on top of that, imagine that the company had to arrange transportation and accommodation for the candidate, because he/she was from another city. Or, the company has a recruiting process that requires the candidate to pass an interview with HR or to take some personality tests first. What a waste!
And it is a global problem – Coding Horror, The Non-Programming Programmer.
The solution? Interview candidates by phone or online first. Coder Proof is a free interview tool that allows you to see the candidate’s skills at programming in real time. You can see how he writes code before dedicating more time and resources to bring him to the office for a face-to-face interview.
And the candidate can run at any time – there is no shame in “I just lost my internet connection”. 
This looks like it could be an improvement over see[Mike]code. I’m going to give this a try in my next interview.
@David:
Thanks! Feedback is welcome.
That’s a really good idea.