These are my criteria for reloading range pickup 9mm. No kabooms yet.
-Check the primer to see what the pressure on the previous firing was like. If it's flattened, don't reload it.
-Any bulges, cracks, splits or "smiley" marks? Chuck it.
-If corrosion comes off with tumbling, it was only cosmetic and it's safe to load.
-Tarnish/scorching/powder burns near the mouth and along the walls are fine.
-If you load it and the primer falls out, it's been fired too many times.
-Check all your loaded rounds with a cartridge case gauge. If it doesn't fit, something is wrong, fix that round or recover components.
9mm is so plentiful, I'm at the point where I throw out a piece of brass if it even gives me a funny feeling, which I admit isn't often.