This is the kind of freelance work I love doing, it's win-win. You get to solve a complex puzzle and the people who hired you are happy that you saved their ass

This is the kind of freelance work I love doing, it's win-win. You get to solve a complex puzzle and the people who hired you are happy that you saved their ass. These jobs often have a lot of simple things you can fix early to eliminate the immediate danger (eg opcode caching) and give you time to really dig in and fix everything.