Happened to me more than once in a new project to come across some old code I didn't like, and when trying to understand it finding out that the old team doesn'

Happened to me more than once in a new project to come across some old code I didn't like, and when trying to understand it finding out that the old team doesn't understand it either and just does things out of inertia. Now what's one supposed to do here, except starting to refactor to get a feeling what dragons there are?