[HNaTTY]

> (legitimate visits, obviously)

That's an important point; I'm seeing referral spam in my GA reports which I never noticed before 2015. I manually discount it when compiling reports, and my understanding is that these spammers hit GA UAs at random without even loading your website.

[snowwrestler]

It's incredible easy to filter this out in GA. Just set a filter or segment that only counts traffic from your known hostnames.