Uncle Bob writes about why rewriting an existing Big Ball of Mud is probably the worst thing you can do:
It’s depressing to think that many of the projects I have been brought in on over the past few years were grand rewrites. Technically they have been relatively successful, but probably viewed by the business as time-wasting and expensive. It’s time for this madness to end! Pick up a copy of Michael Feather’s book and start scrubbing!