The ugliest, most incomprehensible code I've ever see was when I had to mess with RedHat's version of Anaconda (for building distros) back in the early 2000s. It was worse than the multi-thousand line TCL screen-scraper that I had to occasionally fix in 1999. It was the first code I'd even seen written in Python. You couldn't really trace anything, it was all so nested and idiomatic. It made the Perl code I inherited from a long-time Perl guru downright comprehensible. I've looked askance at Python since.