The great wonderful world of Google Analytics Referral Spam & Bot Traffic – the most recent in a long tradition sending irrelevant or inappropriate messages on the Internet to a large number of people. This guide outlines why it matters, what’s going on, and most importantly, exactly what to do about it (skip to that section here).
EDIT 12-15-2016: Google has not developed a global solution. In fact, GA spam is worse than ever. And with the latest wave of spam in November, the most reliable methods are not effective. Your best bet is to keep “layering” all the defenses that I mention below. Additionally, keep learning what you can do with Analytics, and look carefully for spoofed traffic.
EDIT 7-24-2015: Google has announced that they are looking into a global solution. Additionally, Analytics Edge has released a plug and play Advanced Segment for Google Analytics that implements most of what I explore below.
Either way, if you want to understand what is going on with referral spam, keep reading!
You’ve probably recently logged into your Google Analytics account and seen semalt.com, darodar.com, buttons-for-website.com, hulfingtonpost, and countless others in your referral report.
Or, you’ve checked your organic keyword report and seen “ilovevitaly SEM”
Or, you’ve seen a giant spike in direct/(none) traffic that spikes one day then goes away.
Or, you’ve seen visits to URLs that are not anywhere on your site (not even hacked pages).