Believe me, I've seen bad Perl[1]. Luckily I was already very familiar with Perl, so I was able to discern that the developer was just batty.
1: Global variables everywhere. Every function call did not pass arguments, but instead they assigned data to global variables in the immediately preceding lines, called the function, and then used those global variables. Copious use of SQL where every query was saved in a variable called $stmtA, $stmtB or $stmtC, depending on how many levels of sub-querying needed to be done in a loop. Obscure variable names in general. Zero comments. No use of modules, everything in one flat text file (for 5-10 or more flat text files), no code reuse. PHP used in the same project, to the same standard (one large sprawling multi-thousand line PHP file). This was an open source project, and to this day I wonder if possibly it was all a purposeful design decision, so they could charge for development requests.
1: Global variables everywhere. Every function call did not pass arguments, but instead they assigned data to global variables in the immediately preceding lines, called the function, and then used those global variables. Copious use of SQL where every query was saved in a variable called $stmtA, $stmtB or $stmtC, depending on how many levels of sub-querying needed to be done in a loop. Obscure variable names in general. Zero comments. No use of modules, everything in one flat text file (for 5-10 or more flat text files), no code reuse. PHP used in the same project, to the same standard (one large sprawling multi-thousand line PHP file). This was an open source project, and to this day I wonder if possibly it was all a purposeful design decision, so they could charge for development requests.