Well, here we are in May, 2016 and I saw a whole bunch of new sites hitting with referral spam. It is like a growing cancer.
I visited some of the sites and looked up their owners. Most of them come out of Russia for some reason. While I am not anti-Russian at all, I find it strange. Many trace back to the Ukraine and that is expected as they are the biggest spammers. Perhaps they are using Russian servers?
Some were actually good sites which obviously hired some black-hat SEO hackers to spam the heck out of our server logs.
The problem with referral spam is you never really know where or how visitors arrive. Is it legitimate traffic or just from the idiots you hired to get you hits sending you traffic from mad as heck system admins?
Well, if you keep up with out monthly referral spam listings you can get a better grip on who actually is linking to you rather than who wants your traffic to steal money from clients.
Best of luck and would love to hear from you!