Other reasons can be from associating your url with certain “bad neighborhoods” in Google or engaging in deceptive practices. Search engine optimization is a skill divided into on-page modifications and off-page promotion. A common mistake even talented web designers make is to write for the wrong audience. Ultimately a website will have to perform well to a human audience, but if the code underlying the webpage is not written for Googlebot in mind, very few people will ever get a chance to view it.
Webpage creation in 2 stages.
Crafting a functional webpage that’s pleasing to the eye and incorporates Shakespearean isn’t likely to turn a profit if Google’s algorithm doesn’t award your work of art with decent positioning in search results pages. I’m of the opinion that webpages should be crafted to get the page to perform in Google search results first then after it’s located where the most eyeballs can see it, reworked so it performs to a human audience.
Most common mistake is too many keywords.
What are keywords?
Wikipedia says Keyword may refer to an Index term, a term used as a keyword to retrieve documents in an information system such as a catalog or a search engine
How many keywords is too many for your meta tags?
They answer is… it depends.
Consensus in the search engine optimization community is that the more pages, the larger your site is, the more keywords and keyword phrases you can safely use without tripping Googlebot’s algorithm and identifying your site as a possible spam website.
Too many keywords can be just as harmful as too few. Less is more when it comes to the META tag. So how do you choose which keywords to keep? How many keywords should you include?
Ideally, your keywords tag should have ten or fifteen words, twenty at the very most. You may repeat your three most important keywords once, if you like, but repeat them more than that and the search engine is likely to ignore them, or, worse, not list your page at all.
Keyword stuffing is considered to be an unethical search engine optimization (SEO) technique. Keyword stuffing occurs when a web page is loaded with keywords in the meta tags or in content. The repetition of words in meta tags may explain why many search engines no longer use these tags.
Keyword stuffing had been used in the past to obtain maximum search engine ranking and visibility for particular phrases. ..Google no longer gives good rankings to pages employing this technique.
Jill from Highrankings.com offers this “Figure about 3 or so phrases per page. But be careful of just creating junk pages so you can add more keywords.
Matt Cutts the head of spam control at Google has a prime example of too many keywords on his blog here:
Moral of this story?
If you want to utilize all of the great (relevant) keywords you dreamed up, make an additional webpage within your site to maximize the benefit, help prevent alerting Googlebot’s spam meter, and ensure your site’s content is diversified among the keywords you want to target.