Joel's article isn't about clean code, it's about rewriting entire codebases from scratch, which is not the same thing.
"Clean code" in general is hard to discuss because the costs and benefits of it are hard to measure or even make visible. I think in the end most people go by intuition. My intuition is that the costs of crappy code are higher than nearly anyone believes, so I'm fanatical about writing the best code I can. That doesn't mean I would go about rewriting an older module just for the sake of cleaning it up, though.
Joel's article isn't about clean code, it's about rewriting entire codebases from scratch, which is not the same thing.
"Clean code" in general is hard to discuss because the costs and benefits of it are hard to measure or even make visible. I think in the end most people go by intuition. My intuition is that the costs of crappy code are higher than nearly anyone believes, so I'm fanatical about writing the best code I can. That doesn't mean I would go about rewriting an older module just for the sake of cleaning it up, though.