I have several websites that get daily around 5% of visits from spam referrers. There is one strange things I noticed about this referrers: they show in Google Analytics, bu
I think that the most effective way to avoid ghost spam is to add a custom dimension that let you know the site was indeed visited, because as we know they never visit the site.
ga('set', 'dimension1', "Hey I'm really here!!");
ga('send', 'pageview');
You should simply add this lines in your pages and then add a filter to "include" only when the dimension has the expected value ("Hey I'm really here!!") in this case