I made this Shimmerscale farming guide to help out players who want to farm the leathers instead of buying them from the Auction House. I traveled around Zuldazar and Kul Tiras to search for places with high density of mobs which I can kill and drop Shimmerscale. Below you will find a list of places I think are the best for farming Shimmerscale.
The best farming places got nerfed, so I removed most of them from the guide. I'm currently looking for new places. If you see mobs only dropping gray items when skinned, then that spot got nerfed too.
Kill Scaleclaw Saurolisks around the marked area.
Kill Venomspine Saurolisks around the marked area.
Kill Shallows Saurolisks around the marked area.