I always suspect these people are actually looking for developers who will work long hours with little pay, because they are so driven. They aren't looking for the best and brightest, just the most driven.

I think it's actually quite easy to 'care' without having a driving passion that forces you to give your life over to programming. In fact, I did it for a number of years. I did all my programming at work, and all my relaxing at home. And I was happy, and loved both.

Testing for 1 thing because you want something related is a big mistake. You can easily have both false positives and false negatives. And since you're testing for the wrong thing, you won't know until it's too late. If you ever do.