Spam skews data and spoils it so that it can no longer provide you with useful insights about user behavior and your website's performance. It is more impactful to sites that receive less traffic (because if significantly alters the data) than it is to bigger companies that get thousands or millions of views.

Spam in Google Analytics will almost always appear in the "Pageviews" or "Referrals" sections. You can spot them by their suspicious URLs or their names. For instance, what does darodar mean in Google Analytics? The name 'darodar' automatically suggests that your site has been spammed.

Over this year, a rising number of "Referrer Spam" has been tracked within GA. Analyze your visitor data over the last one year and check to see visits from websites like Get-Free-Traffic-Now.com, darodar free-share-buttons, and other similar sites. Your website and almost every other randomly selected site will most likely find these bots in their Analytics. Artem Abgarian, the expert from Semalt
explains how to deal with spam in Google Analytics to prevent them from ruining your data.
Spam in GA usually comes in two main ways - Ghost Referrals and Crawler Referrals

Ghost spam inflates a site's visitor data without visiting the site. They do this by executing the site's GA tracking code and sending it to the GA server directly. The challenge posed by ghost referrers is that they cannot be blocked using your .htaccess file since they don't access the site physically. Ghost spam is usually removed from Google Analytics through filtering.

Crawler referral spam physically visits your site and crawls your webpages. Due to the crawling activities of this bot, your GA report shows like you had a number of visitors originating from third-party domains and they spent a good amount of time interacting with your site.

Crawler spam can visit your site momentarily from time to time. As a result of this behavior, you see unexplained peaks and dips in your traffic data. These bots ignore rules laid down in your robots.txt file. But unlike ghost spam, you can eliminate crawlers by blocking them in your site's .htaccess file which blocks traffic from specific domains and prevents them from reaching your site. Using filters can also help to get crawler spam out of your GA. This is done by excluding the referrer sources you have identified as spam.
What's the idea behind spam and how does it affect your site?

It is important to note that spam can be sent to any site because the main aim of referrers is to lure any web user into clicking them. That's the entire idea behind spam so don't get worried that they might steal your data or something. Most referrers are only after driving traffic to their sites. They bank on people's curiosity, knowing that you'd be inclined to check whatever appears in your GA. Now you know why you should not click any unknown URL in the "Referrals" and "Pageviews" sections of your GA report.

The main effect of spam on your site is skewing your data, or spoiling the accuracy of the information Google Analytics provides. Crawler spam adversely affects your site's bounce rate because the bots always have a bounce rate of 100%. If there is crawler spam in your GA, it definitely means that your bounce rate has been inflated.

There are notorious spam referrers that send malicious code such as viruses. This is another reason to avoid clicking the URLs of referrer spam in Google Analytics.

Even after setting filters and doing everything else to keep referrer spam from your GA, it's important to revisit your data regularly to check whether there have been new suspicious domains. Whenever you find such, add them to your filters and your site's GA reports will become more accurate and useful.