I've suspected this guy was using stolen content for some time, images cropped to odd sizes etc. I was able to finally confirm when he submitted this gallery.
http://www.sweet-sin.com/d/ido6/vt.html
SluttySammi.com is a site I promote myself, so I knew the content was exclusive. I sent her an email and she confirmed that they are pirated images.
He submits using this sweet-sin.com domain and also on porn-service.us using the name neo.