In March this year, Google announced that it had solved the problem of referral spam in Google Analytics.
Unfortunately it quite simply hasn't. The problem is with us as bad as it ever was, some people are reporting it's actually become worse.
Referral Spam works because curious webmasters will visit referral links in order to see where unusual traffic has come from. The spammers may sometimes use these links for malicious purposes other than advertising – some examples have been seen of referral spam pages actually containing malware.
If you do a Google search for ‘referral spam' then you will find many articles professing to show you ways to stop it, however the fact is that without Google actually doing something about the problem then any solutions suggested don't always work.
Filtering referral spam is difficult for the webmaster and at the end of the day only Google can fix this problem.
We'll keep you updated.