Updated 7/1/15.
Starting in mid-2014, a few disreputable marketing companies (mostly outside the U.S.) began a practice of sending visitors to websites they didn’t ask to go to (including probably yours). Over the past year this has become a very big problem on the web because it makes it appear you are receiving more valid visitors than you really are in your Google Analytics data. This doesn’t hurt your website, but it makes it impossible to measure how your website SEO is doing. To see the “bad referrals” you are getting::

1. Log into your Google Analytics account.
2. On the menu on the left of the screen, go to Acquisition – All Traffic – Source/Medium.
3. In the list, you will likely see some of these entries which are distorting your data:

• 100dollars-seo.com / referral
• 4webmasters.org / referral
• adviceforum.info / referral
• aliexpress.com / referral
• best-seo-offer.com / referral
• best-seo-solution.com / referral
• buttons-for-website.com / referral
• buttons-for-your-website.com / referral
• buy-cheap-online.info / referral
• cheatdaddy.com / referral
• cre8withluv.wix.com / referral
• dailyrank.net / referral
• darodar.com / referral
• duckduckgo.com / referral
• event-tracking.com / referral
• fiverr.com / referral
• free-share-buttons.com / referral
• Get-Free-Traffic-Now.com / referral
• googlsucks.com / referral
• guardlink.org / referral
• howtostopreferralspam.eu / referral
• hulfingtonpost.com / referral
• ilovevitaly.com / referral
• kabbalah-red-bracelets.com / referral
• live.yodle.com / referral
• merchantcircle.com / referral
• mozilla.org / referral
• netplexity.net / referral
• okcupid.com / referral
• rankscanner.com / referral
• sanjosestartups.com / referral
• search.xfinity.com / referral
• searchlock.com / referral
• semalt.com / referral
• semaltmedia.com / referral
• simple-share-buttons.com / referral
• sitevaluation.org / referral
• smailik.org / referral
• social-buttons.com / referral
• sonicwall.com / referral
• success-seo.com / referral
• trafficmonetize.org / referral
• urlopener.com / referral
• videos-for-your-business.com / referral
• webmonetizer.net / referral
• websites-reviews.com / referral
• weburlopener.com / referral
• xtopoly.com / referral
• youporn-forum.ga / referral
• непереводимая.рф / referral

You can filter these bad referrals out by:
1. Click on the Admin tab at the top of the Google Analytics window.
2. Click on Tracking Info under the PROPERTY column.
3. Click on Referral Exclusion List.
4. Add each of the bad domains above (e.g., semalt.com, buttons-for-website.com, etc.)

(note: This only works if you are using the newest Universal Google Analytics tracking code. If you aren’t, it’s time to make the change by updating the Analytics tracking code on each page of your website.)

Happy to answer any questions.