Referrer spam (also known as referral spam, log spam or referrer bombing) is a kind of spamdexing (spamming aimed at search engines). The technique involves making repeated web site requests using a fake referrer URL to the site the spammer wishes to advertise.
Swift Analytics will protect your site against referer spam, and help to keep your analytics clean. The plugin uses multiple techniques to prevent referer spam, including on site solutions, online blacklist and user defined blacklist as well.