What makes a piece of code miserable to read?
What makes a piece of code enjoyable to read?
How much of your time is spent reading code?
I just happened to be scanning TensorflowJS and MagentaJS when I saw your post so I'll single them out (and I understand Jeff Dean himself is an active contributor).
Trying to understand how they implement arbitrary neural style transfer (and how it can be further tweaked). It's all quite clear. Not just the math. But the comments are chock full of references to academic papers, blog posts, etc ;)