3 - Say No to Page Cloaking
Cloaking pages is the practice of creating two different versions of an article in order to gain more traffic. While one of the article versions is created solely for search engines, the other is created for human consumption. This is a black hat SEO practice and should be avoided like the plague because it will harm your website.
Even if you're able to fool SEO bots into giving you some traffic, be sure that Google will fish you out. And when it does, there's no way of escaping Google penalties even to the point of removing such pages from its index.
If you've come across a page that has promising headlines but the contents offer no value, that's an instance of a cloaked page.
4 - Don't Indulge in Spam Comments
Agreed, comments are great for keeping visitors much longer on a web page leading to lower bounce rates.
They are also perfect for extending the information that is presented in a blog post or article. It allows readers who have the domain knowledge to contribute meaningfully to the discussions.
That's why site owners go the extra mile, so they can have multiple comments on their pages. While it is a good idea to encourage visitors to post comments, it is a wrong SEO practice to spam comments.
If you find that a blog post has multiple comments yet most of those comments are irrelevant to the post, then you're looking at spammed comments. This is a black hat SEO practice that will attract the Google penalty on your website once this anomaly is discovered.
Whether it is done manually or through the use of software, the spam comment is a fast route to getting axed for violating Google Webmasters rules. Spam comments turn your site into a dung-hill where poops are dumped.