When you are first getting started out with Google Analytics, one thing you may notice is that you are getting all this weird looking traffic, some of which can look like it is giving you a lot of new visitors. This is often spam, and it can come in some different forms.
Referral Spam
Referral spam is a process in which other websites (or promoters hired by those websites) will create bots - small automated programs - that trigger the Google Analytics script on your pages to make it look like they are sending a bunch of people to your website. The whole point of this is that you, the website owner, will look at your Google Analytics data, see their website sending all this 'traffic' to your website, and then go to their website to check it out, thereby boosting their traffic.
Referral Spam Examples
This is the top 10 referrers to my personal blog for the 3 months after launch. You have to appreciate the cheek of using referral spam to get traffic to a website with the URL howtostopreferralspam.eu...
What to do about it
Being aware that this traffic is spam is the first step. Once you are aware of what is going on, you just need to think carefully about which referrers you go to check out. Do not give spammers what they want, which is for you to visit their website and generate traffic for them.
In terms of filtering your Google Analytics data to remove this spam, there are no really practical solutions. You can create a custom report in Google Analytics (Customization -> Custom Reports -> + New Custom Report) and add filters to that report, filtering out the specific referral domains that are creating the spam, but there is an almost unlimited number of spammers and there are better things you can spend your time on then continually adding domains to your list of filters.
So what to do? Well, it turns out that referral spam is typically a problem that solves itself. Either your traffic will grow to a level where you won't even notice it, and/or after an initial rush the spammers give up - it seems that they target new websites because their owners are less likely to know what is going on. Two years after the launch of my personal blog, I get almost no referral spam anymore.
Organic Search Spam
In a similar process to how referral spam is created, spammers can also make their bots trigger your Google Analytics script in such a way that it seems like they came from a Google search. When they do this, they also specify the keyword used, and in this case, it is that keyword that provides the link back to their website or product.
Organic Search Spam Examples
This is the top 'keywords' used to find my personal blog for the 3 months after launch. You'll notice our old friends at howtostopreferralspam.eu are covering all their bases...
What to do about it
The same advice provided above for referral spam also applies here. Firstly, do not give them what they want and visit the website or even search for it. You are generating traffic numbers for them that they are using to sell to advertisers. Secondly, although you could create some custom filters to also filter out Organic Search traffic with certain keywords, do you really want to spend time trying to cover off all the different possible variations? Just ignore it and trust that it will go away, and/or it will get drowned out by the huge search traffic you are going to get.
Comment Spam
This one is not directly relevant to Google Analytics, but for anyone with a Wordpress website, you will undoubtedly be familiar with comment spam. For the uninitiated, blogs and websites with comment sections will often get bombarded with 100s of spam comments. These spam comments can take a number of forms, from hard to detect legitimate sounding comments (the give away is almost always the URL they include with their comment), to absolute trash which is just a list of links to various items being sold by an online retailer.
Example 1 - Obvious spam
This is the easily identifiable trash spam that you will likely be receiving if you have a Wordpress site. They're not even trying...
Example 1 - Less obvious spam
This type of spam is a little bit harder to identify as it can sound like a legitimate comment. However, the fact that you will usually receive dozens of very similar comments in a short space of time, and the URL they link to the comment (blacked out above) is usually the give away.
What should you do about it?
The other difference between comment spam and the other types of spam mentioned above is that comment spam is relatively easy to deal with. If you do not have one already, install a Wordpress plugin to filter out comment spam. Askimet is one of the most popular options and does a pretty good job from our experience.