Unless the marketer is a victim of click fraud, they can make marketing decisions based on bad data.

If click fraud becomes too much of a problem for advertisers, it can in some cases prevent them from serving paid ads.

The wild west of display advertising

Display advertising has been around as long as PPC advertising.

From the beginning of placing fixed banners on websites for a monthly fee, display advertising is now a complex system of AI and sharing.

One of the largest display advertising networks is Google Ads and its Google Display Network. As of 2020, the display network has more than 2 million partner websites and reaches over 90% of all web users.

With the huge demand for display advertising, Google allows webmasters to join its display network with relatively low demands.

As long as they have a clean website with legitimate content, any webmaster can serve ads on behalf of Google.

Compared to Google Search Ads, display advertising is generally much cheaper, but it also works differently.

Instead of the ads that appear in Google's official search properties, they are displayed on third-party websites so that webmasters can generate advertising revenue.

The unethical webmaster

Not every webmaster joining a display network has innocent intentions. Some are purposely trying to play the system and waste the advertisers' spend.

These sites, known as ad farms, are extremely quick and easy to launch.

Currently, every webmaster viewing a network's ads on their website gets around 68% of sales with each click, although this varies from network to network. This means that the webmaster needs their ads to make more money in order to get more clicks.

There are several ways to do this. Some are ethical but time consuming. Others are quick and easy – which means scamming advertisers.

The strategy of many unethical webmasters is to simply click on their own ads. By clicking their ads, they are getting money from networks with no intention of ever buying the advertiser's products or services.

Since clicking ads can be a slow process and most reputable networks have systems in place to stop this very obvious fraudulent activity, many webmasters have gone a step further to create automated bots that replicate human-like behavior.

These bots automatically click on ads without requiring human input while impersonating legitimate users. You can significantly increase webmaster revenue while avoiding built-in fraud detection systems on the ad network.

How to identify ad farms

When you run ads on display networks, manually reviewing and reviewing websites is a must.

Although most networks manually check all websites joining their program, this is usually a one-time process. This means that once they are approved by the network, they can switch to shady tactics and go unnoticed.

If you're struggling to determine if a third-party website is legitimate or an ad farm, here are some strategies that can help.

Use SimilarWeb

The first way to get an idea about a website or ad farm is to switch to SimilarWeb.

This gives you some insight into a website's traffic sources and shows you where most of the users are from.


Legitimate websites usually get most of their traffic from search, social, or referral actions, unless it's a big brand name.

So if you find that a website gets 90% of its traffic from direct visits, it is either a big, well-known website, or something is wrong. It's not a perfect detection method, but it's a good starting point.

Data outliers

If you keep a close eye on the metrics of your display network campaigns, you'll get plenty of pointers about display partner websites.

The most obvious thing to look for is an above average click-through rate. Currently, the average click-through rate on the Google Display Network is around 0.5%, but it can vary depending on the industry.

Ad farms typically have higher click-through rates, often with peaks and valleys that follow the same patterns for weeks.

Visual inspections

The final option to search for potential ad farms is to visually inspect the website. This may seem like a slow process, but it will definitely give the best results.

The most important thing to look out for is where the ads will be placed and how many will appear per page. Ad farms typically go overboard and deliberately stack ads or place ads in front of buttons.

If the website looks like this:

Ad farm

Then it's definitely an ad farm.

Fight against advertising fraud

Now you understand the dangers of click fraud and how unethical webmasters use display ads to make a fortune. How do you protect yourself?

Networks have their own invalid click detection algorithms, but of course they are designed in their favor and not an independent method of verification. If you really want to get the most out of your monthly ad budget, you need to be proactive.

Exclusion lists

Your main weapon against unethical webmasters and poorly performing websites is an exclusion list. By adding websites to this list, you are effectively instructing the network not to serve ads on those websites.

The hard part of this strategy is searching through the potential millions of affiliate sites to see which ones are worth your money.

Using an existing exclusion list is a good starting point to then customize it to suit your own needs.


A new security measure introduced in the display advertising industry is the ads.txt file.

This file lists the Authorized Digital Sellers (ADS) who are authorized to resell a website's ad inventory.

The goal is to empower advertisers who buy ads to address the growing problem of domain spoofing with display ads.

Checking websites with ads.txt files before blind showing display ads is another strategy to greatly reduce the levels of ad fraud.

Although this is by no means a guarantee that the website is "clean". Some ads.txt files are known to contain malicious websites themselves or to be used in schemes like the 404bot.

Allow lists

Unlike exclusion lists, the allow list tells networks which websites should only show your ads. If you are very selective about which website to link your ads to, this is a surefire way to be in full control of your ads.

Similar to the exclusion lists, you may have to search many websites to check them all. But at least you know that your ads will only show on legitimate websites.

Check your PPC campaigns for free

If you run PPC campaigns, you are likely to have been hit by click fraud in your search and ad campaigns.

Fortunately, you can now check your campaigns for fraud completely free of charge with PPC Protect and its 14-day trial version.

Leverage powerful machine learning and neural network systems to identify the fraudulent activity that ad networks and other platforms are missing out on.

Sign up for your free 14-day PPC Protect trial here.


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