Here's the link I followed for my Acura legend to show how easy it was to change for me. I had rotting leaves and dust just like the pictures that was producing the smell.
http://acura-legend.com/vbulletin/showthread.php?t=69148
My GF uses Shining Monkey: Fabric Protector on her purses. She said it makes the bag waterproof so water will bead on the leather rather than soak in. I guess this is very popular way to protect expensive bags.