I dunno... it's frustrating, but really, you can learn some valuable stuff during those few hours.
I have had some interviews that certainly haven't been positive, but they have been instructive or rewarding in some way. Not necessarily even relating to code. It teaches you something about them, the industry, and more importantly, about yourself.
This isn't a fact set in stone. These are objective observations. It completely depends on the goals of those involved. Even in 'bad' interviews, there is an argument that there's value there. Is efficiency trending upwards or downwards in building our professional relationships? It's Impossible to quantify from these anecdotes.
