The industry is full of people who program "for work" but aren't particularly interested in the art of it. Finding people who program in their spare time is finding people who look at the task a bit differently.
Imagine for a moment:
- A construction worker who builds for fun in his back yard
- A woodworker who enjoys making his own furniture
- An architect who draws sketches of imaginary building projects in his spare time
Certainly these people are the exception rather than the rule. You can practice your trade for fun, but many people don't. It's not expected, but you do tend to look at these exceptions as possessing something special. Now let's look at the other side:
Imagine for a moment; would you hire:
- A musician who won't play music if she's not getting paid to do so
- A cook who doesn't want to prepare his own meals
- A painter who won't pick up a brush if not to work on a commissioned piece
When talking about these professionals, it seems out of the ordinary to expect that they wouldn't practice their trade for their own entertainment. Why? What's different? Clearly, these people are (expected to be) artists at whatever they're doing. Painting isn't just a 9 to 5, it's more of a calling, it's practically an identity. And it's special. When you say "I'm a painter," people say "Wow!" When you say "I'm an accountant," people say, "Oh."
When you're hiring, you really want to find a programming Da Vinci. You'll settle for someone who will put in his time to pick up his check, but you'd prefer to find someone who sees his projects like works of art, who does it because that's how he'd prefer to be spending his time.
Of the programmers I've associated with, 100% of the most productive ones work on programming in their spare time. And this difference isn't even close; a single (skilled) programming "artist," even one fresh out of of college, has the same average productivity after 1 year as a decent-sized team of experienced "at-work" coders. It can be embarassing.
So, when I hire, do I ask if they program in their spare time? Hell yes. Not directly, of course; that can be faked. Rather, I ask them to show me a project (and source code) for something they've built on their own. I ask them to explain what made them decide to write it, how they went about finding information on how to do it, etc. For the artists, this is like asking them to tell me about the time they won the lottery. You can really tell the difference with the people who do this because they love it. Not all "artists" are good at their art, but the ones who are can make a huge difference.