Spam, Junk in Google Analytics
Generally people strongly dislike spam. We dislike them as well. Especially in Google Analytics it can make it hard to focus on the most important data.
Referral spam are nothing else like fake traffic. Sessions are coming from fake websites.
How to deal with them?
Firstly check all your domains tracking code than create a list of all the places where your Google Analytics tracking code can be installed. Secondly turn this list into a Regular Expression.
All you need to do is type in each domain, then put a backslash before any full stops and separate each domain with a pipe (|). When you’re done there shouldn’t be any spaces between the domains.
You should track only traffic from these domains. Navigate to ‘Admin’ and ‘Filters’ within your reporting view. It is important to add the filter and select ‘Custom’ as the filter type and select ‘Include’ after ‘Save’
This process will help you to remove most of the junk coming into Google Analytics.
Also you need to exclude all the currently known spam sources using custom filters and fake language codes. It is time consuming but well worth to do so.