The Rodent icon theme seems to be designed to be based on the Gnome icon theme. For instance, the Rodent home folder icon has a brownish color that fits the rest of the Gnome icons. After a recent update, when Tango is installed, Rodent prefers to base itself on Tango in Xfce, which yields some awkward color combinations. An easy fix is to change Inherits=Tango,gnome,Industrial to Inherits=gnome,Tango,Industrial in index.theme
xfce4-icon-theme is deprecated and was dropped from xfce4-meta. that said, we won't be doing any modifications to the icon theme and we wouldn't otherwise either as it's upstreams decision to pick Inherits order. # emerge -C xfce4-icon-theme