OnionSEO - 3:16 pm on Dec 19, 2011 (gmt 0)
Thanks for your reply Ian.
I believe I have an account of what is going on now. We started a campaign doing display ads on an ad network. The very next day we started receiving traffic from these spam sites. I believe that the spammer discovered our website through these ads, and started "referrer spamming" us in hopes of getting linkbacks.
This would explain why we continue to get traffic from these spam sites even though the display ad campaign has been shut off.