I might be in the minority, but I've learned to love the challenge of taming a beast of a code base.
Coming in and helping out people who don't have *anything* in place and slowly adding order has a satisfaction level all of its own.
Building out a test suite as we document business logic and then planning a refactoring can be rewarding too!
"For a male and female to live continuously together is... biologically speaking, an extremely unnatural condition." -- Robert Briffault