"Use this tool to scale selected polygons perpendicular to their Normals. Use this tool interactively by dragging left or right within the viewport. You can also drive the tool with numeric input."
It only scales polys in relation to their normals and with every poly selected it looks a lot like a regular scale. Try it on a standard sphere and you can see the difference with every poly selected. I think it's most useful for selected islands of polys.