The shadetree mechanic won't mind doing a quick oil change if he doesn't get filthy in the process. Muir's words hold wisdom for programmers. Clean code is a joy to maintain. It's clear what each line does, and there's little worry that a minor change will cause major problems in some other part of the system. Above all, clean code is pretty.
Pretty code follows some indentation standard, so the structure is visible with a glance.
Pretty code is never overly indented - twelve nested IFs are too many for any mere mortal to understand. One of C's weaknesses is its free form - it does not encourage pretty comments. In assembly language tab stops insured that with even a tiny bit of effort the comments all line up on the right side of the code. Writing pretty assembly code is easy. I really like assembly's right hand comments, since one can scan down the page and immediately pick out the purpose of each line without ever reading the code itself.