Google Analytics spam is a headache for many website administrators. Spamming techniques constantly evolve since 2014 when referral spam started with bots from semalt and buttons-for-website that visited your website and left fake referrals.
In late 2016 we saw language spam where spammers manipulated
Accept-Language HTTP header with entries like o-o-8-o-o.com search shell is much better than google!” or Secret.ɢoogle.com You are invited! Enter only with this ticket URL. Copy it. Vote for Trump!.
Carlos Escalera, Google Analytics expert, writes articles about SEO and Google Analytics and has written an excellent step-by-step guide to exclude irrelevant traffic from reports – Ultimate Guide to Getting Rid of All the Spam in Google Analytics.