I think we are typically not as good at spotting good code as we think we are. For example, I inherited a large code base I while back and thought the classic

I think we are typically not as good at spotting good code as we think we are. For example, I inherited a large code base I while back and thought the classic "I can do better than this". After a few hours of hacking together a demo, only then could I appreciate the existing code base and how nice it actually was. I think in general I look for a good level of abstraction - but not too an insane level. The best measure is how quickly you can understand it, and how long it takes for you to contribute to it.