what makes the distributer go bad?

What makes a distributor go bad? Worn bushings will make the distributor itself bad. A faulty ignition module, or pickup coil(pole piece) does not necessarily mean a bad distributor. Those are pieces within the distributor assembly, that are usually serviced seperately. Often times, the distributor is cheaper, due to less labor involved. With a new(reman) distributor, you should have new parts, and then it is just R&R, and set base timing.