The "nap" is a man-made fiber, probably a plastic derivative, which is VERY sticky, trapping bits and pieces that stick to it, and the nap cannot be brushed/combed without ripping it.  If you vacuum the rug, the fibers just become more stuck together and matted.  I've had it for less than a year, and it looks all matted and unsightly--not like when it arrived.  I am working with a rep at Wayfair to replace it.