The search engines don’t take kindly to sites that try to manipulate the search results in their favor. Black hat SEO firms and spammers are constantly looking for new ways to twist the ranking factors. For instance, having a lot of links pointing to your site is important for SEO, so spammers get links from low quality, spammy sites to boost their link number. Never mind that these links are coming from spam blogs, they choose quantity over quality.
1. Throwaway domains
Google specifically warns against throwaway domains in their SEO Webmaster Guidelines. A throwaway domain is a domain that has very little real value, and is just used to build link popularity to a second site. Many black hat SEO firms will use throwaway domains to build up links to one client’s site, only to redirect those same links to a new client’s side when they lose the first account.
2. Doorway pages
A doorway page is built to make one site more relevant for numerous search queries by stuffing it with keywords. This page is not part of the site’s navigation (meaning no visitor could find it), but it is built into the site structure so the search spiders can crawl it. Sites that use doorway pages to make it look like they are more relevant are often de-indexed once the search engines realize what they are doing.
3. Keyword stuffing
Repeating the same keyword a hundred times on one page of content may make it appear more relevant to the search engines, but it absolutely kills the user-experience. The search engines aren’t looking for a magic number when it comes to keywords. Stuffing your content will only hurt you in the long run.
4. Duplicate content
Some duplicate content was created on purpose (stealing another site’s article and claiming it as your one) and some duplicate content is an accident (homepage.com and homepagedefault.com). Either way, duplicate content can get you in a lot of trouble with the search engines.
5. Dead links
Nothing is more frustrating for a visitor then running into dead pages all over a site. The search spiders will also discover these links and flag them.
The people behind the search engine algorithms are some of the best in their field. They know that the spammers are just waiting to exploit a loophole in the system for their benefit. That is why they are constantly updating and tweaking the algorithm to make it better and, in a sense, smarter.
I’ve spoken with numerous site owners who don’t understand why their competitor (who is employing black hat SEO techniques) is outperforming them in the SERP. I have to keep reminding them that success gained from spamming is short lived. Sooner or later the search engines catch on to what they are doing, and the site will suffer because of it.