Google Analytics – Language (not set) & Sharebutton.to

Filters based on countries or the name of the spam are not efficient because both can be easily changed by the spammers.

Also, it isn’t possible to filter the (not set) entries in Analytics, this label is added after the visit is recorded when Analytics doesn’t find a value for that dimension.

Instead what you should use

• One hostname filter, this will help prevent the majority of the spam, whether it shows as referral, page, language, etc. and independently of the name used by the spammer.
• A source filter for the sneaky crawlers which are far less frequent.

Here you will find detailed instructions on how to create the hostname filter and other measures you can take to prevent fake traffic.