Been there and doing that. . .
For all sinks and showers, I replace the exposed plumbing with new. This is particularly true for new ABS tail pieces and p-traps and angle stops. All faucets and shower mixers get replaced too.
This is not just a liability thing . . . it really helps buyer appeal because it gives the sense of a well upgraded/repaired house. You have to assess things like granite or plastic or tile . . . new counter tops and sinks . . .
Also, I replace every receptacle and wall switches routinely. Presents a clean and updated look that buyers do notice. These items are cheap and easy to replace but the impact is a big plus.
Have fun . . .