Every time I've done that I can never quite figure out if the guy who wrote it is a tremendous genius or a complete fool.

For me that has motivated the biggest improvement in my own coding - writing and maintaining a system for a few years. If I go back to code I have written a few months ago and it doesn't immediately make sense, then i have no one else to blame but myself (I usually refactor it when this happens).

Ghaa my eyes. It burns.