I've been fixing other people's code for fun and profit since 1986 and 1996 respectively. Doing anything from Commodore BASIC to HTML5, from assembly to Scheme, I always tended to gravitate towards languages that were popular and yet misunderstood, with countless examples of code in desperate need for improvement.
Back in the day, in the ancient era of CGI scripts, Perl was my language of choice, an easy target to find bad code in a good language. Then PHP started to dominate in the bad code market and still is one of the best environments to look for code to fix, but the language itself is not as fun as Perl.
I'm always looking forward to fix programs that are broken in new, interesting and creative ways.