When I was an undergrad with a part time job helping out in a graduate chemistry lab, there was a suite of utilities written in FORTRAN. People depended heavily on this suite to calculate all manner of things related to their crystallography research.
The problem was, it was mostly written during one of those years where Lord of the Rings and the Hobbit were massively popular again, and people were learning to program with hunt-the-wumpus teletype programs. The original author "amused" himself by naming pretty much anything he could after some fantasy concept. CASTLE, FRODO, DRAGON, and so on. Okay, so to map out van der Waals surface strength, you ran CASTLE. Many things have quirky codenames, you get used to it. But all the variables followed suit. Now it was a bit more obscure to maintain the program or trace the logic.
Worst of all, the comments. In FORTRAN, columns 1 to 72 were for your program, and anything after 73 was a comment. The author wrote an "epic" of his own, all word-wrapped in the column space from 73 to 132 (the width of common teletype paper and long Hollerith punch cards). What a waste of his time, you might think. But it was also a huge impediment to maintenance; you see, people in the lab LIKED his story (for a while), so they had to figure out how to patch the logic without breaking the flow of the story. It took years before someone stripped all the prose and got the rest of the lab to follow the maintainable fork instead o the prosaic one.