If you are WordPress users, even WordPress addict, I bet that you will know or heard about WordPress security plugin WordFence at least one time.  In August 2017, a company behind WordFence published an interesting blog post named "404 to 301 Plugin Considered Harmful". It revealed a fact that 404 to 301 plugin injected advertising into pages on WordPress site where it is installed. Unfortunately, those advertisings are all for low-grade and potentially scammy services like escort agencies or payday loan companies. However, one thing I want to emphasize is if you also a WordPress site owner, you visit the sites using 404 to 301 Plugin, you will not find the trace of injected advertising. Why? The reason is the code of this plugin was sneakily designed to show the ads only when the page is loaded by a search engine crawler. We call this technique by Cloaking and the giant Google doesn't like it and seriously discourage.

The case of 404 and 301 plugins has caused the interesting but considerable controversy, especially after the blog spot of WordFence was published, as I understand about the content of the blog, it was about the scope of the problem and the apparently deliberately malicious ads injection.

However, I feel more curious and interested in the case that: when I visit several WordPress websites and talk with website owners who do not feel annoyed with Cloaking, they find no problem with this guy.

Working principle of Cloaking is detecting users and programmatically showing or hiding content depending on those users are web browsers or a search engine crawler. So what is the purpose? For influencing search engines. Cloaking cheats search engines and spams their indexes.

I think that I don't need to say or explain, you still understand that this trick will be hated so much by the search engine. While it tries to understand accurately the content of the page, Cloaking makes it possible. If Google recognizes a site engaged in Cloaking, they will almost penalize immediately.

Today, I find a lot of site owners decide to ignore Cloaking and roll the dice on not getting caught. But, I want to emphasize that if you care about traffic and the domain's reputation as well as long-term development, try to avoid Cloaking as soon as possible.

Which case will not be counted as Cloaking?

If you design your WordPress site to show different content for different targeted customers, the content might be changed follow location and segmentation customers for advertising, time of day, the user’s history and a variety of other factors. With Google, this behavior is not Cloaking. It is crucial to understand and remember that cloaking is a deliberate attempt to deceive search engines. So, don't worry that innocent personalization will affect negatively to your SEO strategies because content personalization is not usually deceptive and done by almost every large site on the web.