Just wanted to share from my own personal experience of having had more than one affected bag and more than one replacement, that the "dry powdery feel" was not a distinguishing factor in my bags at all.
One of my replacements which tested perfectly fine with no smell DOES have the dry powdery feel. One of my affected bags which needed replacement did NOT have the dry powdery feel and had plump "bouncy" grains.
So even though these characteristics true for Jadeite's bags, I'm not sure if this would be an accurate "test" for all.
Agree. It's not so much the leather as the treatment process which has been distinguished as the most likely reason for these issues.