It is the combination of color, shape, and sheerness of the fabric that push it into underwear territory for me.
I've been eyeing another dress of theirs-
http://shop.nordstrom.com/s/vp.....ltback=228
I'm sure I will look like a well-heeled potato sac in it though.
I just realized that the company is VPL, as in Visible Panty LInes. I guess then the whole point is to look like you are wearing underwear?