I'll put it this way.....
if you reach into one of my ammo cans & grab a great big handful:
You're gonna come up with this kind of random:
45+ unique HS & probably a bunch more in there. If I were ultra picky or thought sorting by HS was a good idea, Id have a couple 100 round boxes & just load 9mm continually
Here are 5 flavors of FC brass - all living in perfect harmony. If I were discarding perfectly fine brass "cuz hard" - esp early on when I had none & was scrounging - I'd be filling fewer 30 cal cans today. IF someone is trading you 9mm brass - you can bet a bunch of it will be this unless otherwise specified
I was glad to get it regardless. Same for WCC or other crimped - like .223, deal with & move on.
Unless berdan primed, steel, aluminum, or damaged, the only thing I otherwise cull is this. I mentioned in other thread there is a reason, but I don't remember what it is. Early on, it gave me trouble so I said "trash it all". Bad pic, but HS looks like nny-87. Obviously this one is fine - been loaded & shot many times, but there are very, very few others that HS in my mix.
I think your chance is pretty slim of finding brass cased, boxer primed, good condition 9mm brass in the wild that is just plain unusable.... But you might be a lot pickier than I am. Not saying EVERY brand out there is just fine, but completely unusable or should be trashed on sight is very small amount.
Not saying I disagree with others that 9mm is so plentiful it's no big deal to just discard vs spend any extra processing time. But along that line of thought, @ 14¢ round for basic commercial FMJ, why load it all? I think I save $30/case loading vs buying general FMJ training 9mm - and that's buying components in bulk, scrounging to get lowest cost/round. To me, if I'm going to bother loading 9mm, its to do something productive with my time so if processing some brass is part of that, don't really care. When all I had was LCT press, it often was simply not worth the $30 vs the time it took to take 1k from range pickup to finished rounds.
If you are really worried about it, just buy a case of commercial Win white box, UMC, S&B, PPU, etc. Those 1,000 pieces of brass will last an extremely long time. Cost would be the same or less than buying 1k mixed 9mm brass & components to do just 1k