[mildtrepidation]

tl;dr Things you should never do: rewrite the code from scratch.

Sentiment like this is not valuable. The experience that it comes from is often informative, but as a conclusion, this explicitly ignores circumstances that sometimes do make rewriting a good, compelling course of action.

Truly bad, unmaintainable code exists. It exists on projects that have long intended futures. It exists in all sorts of environments on all sorts of projects for all sorts of reasons. To discount the idea of a rewrite out of hand is a failure to objectively review the specific circumstances around whatever it is you're working on.

Often there are better ways, and yes, often a rewrite is a bad idea. But absolutes are so rarely valid, and this one is most certainly not universally true.