Sure, but then, almost all interview questions can be similarly gamed. If an interviewer asks me to "walk him through my resume," or to "Tell him about a time when I did X," does he really expect that I haven't thoroughly prepared and rehearsed those answers? And if I truly haven't, then that's saying quite a bit about how seriously I take the process.

I'm not suggesting that brainteasers are as valid as other question types. There are plenty of question types that better get to the heart of the candidate's aptitude, experience, skills and capabilities, domain knowledge, and so forth. But everything can be rehearsed for. I don't think that's a valid categorical critique of the puzzle type.

Better arguments against puzzle questions, IMO, are: 1) They might select for good bullshitters, as opposed to good thinkers; 2) The opportunity cost of spending time on a puzzle question is the time that could be spent on a more relevant question; 3) Some people just aren't good at (or interested in) puzzles, but that doesn't mean they're not awesome on the job -- ergo, passing on a candidate because he flunked a puzzle is much sillier than passing on a candidate because he flunked a technical exercise. (Conversely, loving a candidate because he kicked a puzzle's ass is even sillier).