Symbolic link icons don't update
I had this problem and the following seems to have resolved it. I'm not sure if steps 2 and 3 are both required so you can try one and then the other if you prefer.


Remove symbolic links
Clear your icon cache:

sudo find /private/var/folders/ -name com.apple.dock.iconcache -exec rm {} \;
Clear your caches:

sudo rm -rf /Library/Caches/*

sudo rm -rf ~/Library/Caches/*
Restart
Recreate symbolic links