I kept the clean ones in the attic, out of the way right next to the pull down ladder,
and the dirty ones in the garage on the bottom of a stainless steel cart, when I get ten or twelve dirty kegs, I would set up the keg washer and spend an afternoon cleaning kegs.
First a rinse through both tubes, knock the big stuff loose with a brush.
Put on the keg washer, with the lid in the wash tank, keg washer also pushes cleaner through the diptube.
Rinse, then fill with starsan, push it into the next keg with CO2, leaving the keg pressurized ~25 psi
Then clean kegs go back into the attic.
Full "on deck kegs" in a climate controlled area ~72*
BTW-I have 45+ kegs and 16 taps.
I still look for kegs and buy them up as I run across then, if they are a good deal.