There’s an acceptable limit for keyword density in SEO (search engine optimization) and if you go over that density, or just have lists of keywords on your pages, blog posts, or articles, you may be penalized by the search engines.
In addition, keyword stuffing generally makes your articles, blogs posts, or pages unreadable or otherwise unpalatable for your real customers, so they will move on to other pages, blog posts, and articles that are easier to read.
So if you’ve stuffed keywords or used other blackhat SEO techniques not only have you gotten penalized by the search engines you haven’t made as many sales as possible. If you are offering something to download or want people to sign up for your affiliate opportunity, these tactics won’t have created interest in your downloads or your other opportunities.
It’s a lose-lose situation all the way around, when what you really want is a win-win situation (actually, there are at least three parties that need to be happy here: you, your customers, and the search engines).
Keyword stuffing is defined as loading pages with keywords; the keywords may be found in the tags or in the content. Either way, Google in particular will not give you good rankings on result pages if you use this method.
It used to be that there was a certain keyword density that needed to be aimed for, and this density was a function of how many times the keyword appeared in an article or blog post compared to the total number of words in said article or blog post.
Things have changed somewhat now, and words that aren’t commonly used are simply going to have a higher value than those that are used more often. In addition, repetition of keywords that occurs naturally throughout the articles or blog posts can have a positive effective on results for those keywords, but there is a fine line between keyword repetition and keyword stuffing.
If you use relevant keywords too little throughout an article or blog post, the article or blog post may be irrelevant to search engines and to your customers; if you use the same relevant keywords too much, the article or blog post may be seen as spam. The trick in getting good results from your usage of keywords is finding that spot between too little and too much; a second trick is using relevant keywords.
If your article is on ice cream, make sure your tags and keywords are related to ice cream, not cows or farmers. While the cows and farmers do produce the milk needed to make ice cream, using cows or farmers as keywords in an article about ice cream may leave your customers shaking their heads.