It's totally fine to use spokes that have been bent, as long as it wasn't a severe bend. In some situations it's actually required to bend spokes a bit to lace them.
The real issue is not that the spokes themselves are bent, but that they're bent while laced to the wheel in what should otherwise be a proper configuration. Normally, if you lace a wheel with bent spokes, the tension they're under forces them to straighten out. If you have a built wheel with visibly bent spokes, this means that either the overall spoke tension in the wheel is significantly below what it should be, or the rim has been deformed so the bent/loose spokes are attached to a bent/flatspotted area of the rim.
Unless the spokes have been scraped/gouged, they will be fine. It's a lot more likely that it's the rim that's messed up.