Finally, thanks to your post, I found the answer to my very long problem. Spams are literally my enemy and I have been looking around to find out how to eradicate or even just to lessen the number of spams that Google Analytics are incorporating. Thank you so much for this very useful info.

We have started to see spam event data, and it seems to me that those visitors are the ghost spammers who don’t actually visit your website, but instead simply cycle through as many Google Analytics ID numbers as possible. That’s why the browser isn’t set (although I’m guessing they could spoof that), but it’s also why the hostname isn’t set—they don’t know (and don’t care) what website you are on, because they aren’t actually visiting it.

Using an include filter by hostname has worked pretty well for us so far.

Jacob

Thanks for looking into this, Analytics is becoming a real annoyance for us. I have looked at my Event spam and then compared this to the traffic with browser value of (Not Set) and I get a much larger number of (Not Set) traffic so the filter would exclude other traffic to. I am wondering if traffic from apps is excluded using this too.