Well, after 23+ year of Infantry and Engr service, I had a few mags that accidently got “crushed” to get them out of circulation, but most were tested with a few mags full before my comrades and I kept them in our personal kit.
I can honestly say that the vast majority worked, and when kept in personal equipment, worked for a long time!
Buying surplus or gunshow stuff usually is a waste of time and effort/$. (Think of how they got to teh show-discarded by the Army and sold as salvage mostly!)
God Bless.
I always test new mags with a full dump, just to be sure.
However, aluminum mags really are the weak link.
Almost every FTF I’ve experienced has been caused by weak or cracked feed lips or an otherwise out-of-spec mag.
Finding a few that work well and keeping ahold of them is fine, but even NIW USGI are risky.
My experiences with some of the newer mags has been excellent, especially in terms of feed lip deformation (none) and cracks (none).