Most junior level developers these days have open source code to look at it (as schools really push that). For higher-level developers you can ask more complicated and telling questions.
That's good and valuable, and it's laudable in its own right in a way that basketball isn't (since open source is a contribution to the intellectual commons) but it's not the same thing as working with someone. A lot of people only publish the projects where they were happy with the results, and often it's hard to tell how long someone took or what kind of help they had when they were writing something.
