I've done it and the wheel went out of true quickly which did not happen when I used new spokes. I have read many people say if you are swapping a rim over (same for same) you can reuse spokes as long as you keep the spokes in the same place then every thing should be find. I have also read something to do with spokes becoming work hardened and that is whey unless they go back in the same position you should not reuse spoke. I don't know about work hardening to comment on this.
I've done it and the wheel went out of true quickly which did not happen when I used new spokes. I have read many people say if you are swapping a rim over (same for same) you can reuse spokes as long as you keep the spokes in the same place then every thing should be find. I have also read something to do with spokes becoming work hardened and that is whey unless they go back in the same position you should not reuse spoke. I don't know about work hardening to comment on this.