8 out of 10 died from illness not bullets. Stuff wore out fast not because it was inferior but because they were 100 times more active than we are. Marching up to 60 miles in less than 24 hours, never washing your clothes or taking a bath, and sleeping with everything on without a blanket or tent tends to be hard on gear.
To some extent that is true. But there are plenty of letters, diary entries, and mémoires that comment on how cheap, shoddy, some of the uniforms and shoes were. Complaints of toes going through the ends of socks the first time they were worn, pants falling apart, jackets falling apart or dissolving in the rain. Single pegged shoes that last ten miles. About the only clothing I haven't seen complaints about are the shirts. North or South, doesn't seem to matter.
Clothing did get washed (often boiled in camp kettles - gave the coffee or soup a 'special' taste) periodically, just not as often as we wash it now. And mending was a never ending task. The old saw "A stitch in time saves nine" was taken to heart. Catch tears or holes when they are small and it takes five minutes to repair. Wait a day and you might spend half an hour on the same mending job.
Same with bathing. If nothing else, sluicing off with water every day or two if you had access to a lake or stream. And trying to wash hands and feet every day. Several manuals recommend that.