> I have maintained 200k line Perl programs written by someone who never stopped to ponder anything outside the problem domain

Ditto, though I think I have a unique element to my story.

I spent a week deleting code I couldn't detect a use for. I nuked nearly 40,000 lines and could not discern a difference in functionality (though, couldn't be certain since I hadn't completed the test suite.)

Writing a test suite for software with no spec and only others' vague recollections of meetings to go on (Agile!) is fun - it basically ends up a regression suite enforcing current broken behaviour.

Perl takes no part of the blame for this, some of the Rails code needs to be seen to be believed - looked like an early PHP tutorial in places.

What was great was, the Perl was full of comments about how much easier it would have been in Ruby/Rails because he never bothered to read the docs on references.