I found 6 boxes of PMC 50AE ammo at the local pawnshop for a reasonable price. I am thinking of buying them, so I have a reason to buy a 50AE Desert Eagle. So far I am resisting, but I am a weak man....Its a sign that somebody "needs" to get a 50.
You could be like, Really? A 50 sucks? 
Take the inaccurate cliché back. 
We assume those are factory? I only trust my own reloads.
Yup, factory ammo
That's on the level of handing a kid a lightweight 12 gauge single barrel shotgun and a high brass high velocity goose load as their introduction to shooting a shotgun.
If I witnessed something like that, from start to finish (someone buying a box from the range and then leaving it partially full at their shooting position), I would probably be willing to scavenge that ammo and actually use it. That's about the only circumstance I can think of where I would.
^^^Yep, same here. Could be it was reloaded ammo and it didn't perform worth a hoot. Could be the guy thought maybe he over charged the rounds. Some folks have deep pockets and lots of brass so throwing it in the trash is easier than breaking it down. Same could be said if it's poor perorming ammo from their firearm. Why keep it? Just to make noise? Like a cheatin' wife, you kick it to the road and move on. while I'll pick up all the spent brass I find, even those calibers I don't reload for. Many times, it ain't worth the hassle of breaking down a round or two of loaded ammo just for the brass. Others are free to feel differently, but my time cost me something. Besides.....I hate it enough breaking down my own mistakes.
I definitely see your point. Before the ammo/component shortage if I was at a traditional range and found live ammo I would just turn it in at the counter. If at an unsupervised range, it it was just one round of pistol ammo I might pick it up and keep it for tear down, but more often than not it’s usually ammo from some eastern bloc country. That crap goes in the trash.
These are the exact reasons that I won't shoot found ammo. I pick up all that I find, take it home, and break it down. Unless its a cartridge that I don't have in my collection, then it gets polished and put into my case. I won't even shoot 22's that I find because I don't want any dirt or grit going down my barrel. I twist the bullet out with Lineman's pliers, the bullet goes into my next lead "smelting, and the powder goes into my jar of "Deer Camp campfire light show" powder.
My wife found 6 rounds of 32 acp sitting on her bookshelf. Asked me what I was going to do with it, why I hadn't just shot off those 6 rounds. Told her I didn't have a 32 any more. I told her I was going to buy a 32 someday to shoot off those 6 rounds.
A buddy, who maintains our indoor range, regularly sweeps up the sorta burned powder that accumulates on the range floor, and he'll take it down to camp for the same purpose.
I have heard of that sabatoged ammo too. I heard it was created in the Vietnam War, left in Viet Cong stockpiles. IIRC, the rounds were filled with plastic explosives.
Probably the only "safe" found ammo to shoot...
I seen a young guy at the range buy 2 boxes of 45 Colt. I was trying to follow him and see if he was dumping his brass or keeping it… anyway, the range was incredible busy and he left before I can Brass troll him!
