If I were building a wheel for someone else, esp. if for pay, then I'd insist on new spokes. No way of knowing what stresses they may have seen before and I wouldn't want to have to later fix any problems that may have been due to existing spoke issues.

But if I'm building a wheel for myself I have no problem reusing spokes that I think are in good shape and are the proper length. This is more common with a replacement of the rim since they wear out from brake wear and then I can leave the spokes in their original position in the hub as I move them over to the new rim. What happened to your hub?