How to reproduce (I'm on Quantal):
This results in an arrow as big as the icon: $ ln -s /usr/share/icons/Humanity/apps/32/bash.svg . $ nautilus .
This results in no arrow at all: $ ln -s /usr/share/icons/Humanity/apps/16/bash.svg . $ nautilus .
How to reproduce (I'm on Quantal):
This results in an arrow as big as the icon: icons/Humanity/ apps/32/ bash.svg .
$ ln -s /usr/share/
$ nautilus .
This results in no arrow at all: icons/Humanity/ apps/16/ bash.svg .
$ ln -s /usr/share/
$ nautilus .