DHH writes a piece I can agree with whole-heartedly.All code will eventually go stale
Here’s something I don’t say often: Suck It Up. If you work on more than a few projects, they can’t all smell like today’s fresh linens. It doesn’t mean you’re a bad programmer. It simply means that you’re prioritizing.
Yes, yes, you should clean up around you when you dive in to those older applications, but beware the lure of a full Spring cleaning. You’ll get pulled in and before you know it you’ve broken half the application and won’t know how to get back out with your ego or tests intact. Add your feature, fix your bug, and leave everything you touch in better condition than you found it, but that’s it. Move on from there.