If you mean "rewrite from scratch", believe me, it is the worst thing you can do. I speak from experience, it is tempting but the few times I have done that, a few months later as I get burnt, I could only think of how an idiot who never learn I was.

Legacy code is like that because it went through many bugfixes and addressing weird requirements. Start over and you lose all that history, and it is bound to repeat itself. That weird feature that makes no sense, as it turns out, makes a lot of sense for some users, and that why it has been implemented in the first place. And customers don't care about your new architecture and fancy languages, they want their feature back, otherwise they won't pay.

Another way to look at it is when you asked to maintain a legacy code base, that's because that's software that has been in use for a long time. If it was that bad, it would have been dropped long ago, or maybe even cancelled before it got any use. Respect software that is used in production, many don't reach that stage.

Of course there are exceptions to that rule, but the general idea about rewriting from scratch is: "no" means "no", "maybe" means "no", and "yes" means "maybe".