there is a risk x consequence thing going on here. I'd happily straighten kinked spokes and re-use those, (in my own wheels especially) provided the likely consequences of spoke failure were not severe.
The reason for this is that
a) the risk of breaking a spoke in a well-built wheel(*) is very small indeed and
b) spokes are manufactured by being cold-formed anyway and
c) spokes get kinked all the time, and don't seem to ever break at the kinks; there are always other places in the spoke (e.g. the threads and the J bend) that are more vulnerable to breakage than that anyway.
I've both built and dismantled many wheels; I've seen plenty that looked OK but they have been built the wrong way, i.e. so that most of the inside spokes had to be 'laced' into the wheel (which is difficult to do without bending them permanently) and these spokes immediately return to their horrible kinked and bent state once the wheel is detensioned. I can nonetheless count the spokes I have ever seen broken in places other than the elbow or the nipple end on the fingers of one or two hands.
If you have a gradual bend you ought to be able to straighten it using your fingers. If there is a more abrupt bend it will be more difficult to remove (the material work-hardens where it is bent most, so is least likely to 'unbend' perfectly), but you can do it; gentle tapping with a hammer with the spoke on a flat surface (eg the back of a vice) ought to do it. The straightened part of the spoke will be full of nasty stresses but these are no worse than those in the J bend of a new spoke and the stress relief that you do will do on the built wheel will sort that out.
(*) In a well-built wheel take the tension and trueness as read, but in addition the J bends fit the hub properly (use spoke washers as necessary), the spokes are set to the correct angle near the flanges, the spokes don't kink as they enter the nipples, and the wheel has been extensively stress-relieved (eg by spoke squeezing). The stress-relief mitigates the extent and effects of any residual stresses in the spokes, including those arising from original manufacture and any forming/setting/ straightening you might have done.
There is of course always a chance with a set of used spokes that one or more is already cracked in such a way as they will fail no matter what you do with them. IME such spokes fail within a few hundred miles under heavy loads and at most a couple of thousand miles. Thus if you have a wheel with unknown spokes or a set of spokes in which you have already had a breakage, you can stress relieve the spokes and if the wheel survives for that distance then you can assume the remaining spokes are OK.
The only exception to the above is if the spokes are made badly; I have seen about half a dozen sets of reasonable quality (stainless steel) spokes (ever, out of thousands and thousands) which were badly made so that the spokes were at risk of breakage regardless of what was done with them.
Bottom line is that if a single spoke breakage is likely to be a big problem (eg you are building wheels professionally, the wheel is likely to collapse if a single spoke breaks, or you don't expect to be able to replace a broken spoke when needed) then by all means fit new spokes all round. But otherwise don't sweat it, go ahead and reuse the old ones, straightened if needs be.
cheers
