Reason that Ruin Your Google Reputation or Ranking

1. Cloaking

You can design your website to be efficiently catalogued by Google, and you can specify which sites should be cached or ignored by Googlebots. Designing your Web site so that search engines see one thing and visitors see totally different content is called cloaking. This can be done with redirects or with programming, and it's strictly verboten.

Nobody likes to be tricked this way. If they're looking for a website on knitting, they'll be very ticked to end up on a website about horses. Or ads. Let's face it, the redirected site is never about anything fun.

Cloaking your Web site is a sure-fire way to get banned from Google and probably the worst thing you could do for Google.

2. Duplicate Content

Spam sites sometimes try to collect page views by duplicating the same content on multiple pages.

Don't copy and paste large amounts of text from your own pages, and certainly don't violate copyright by copying content from elsewhere. Google has been known to ban sites that duplicate too much content or at least severely penalize their ranking in search results.

This can occasionally cause problems, because some spamming Web site might be duplicating your content. If you find someone violating your copyright this way, you can let Google know.

3. Have a Robot Write Your Web Site

Just as it's a bad idea to duplicate content, it's a worse idea to get a machine to write your content for you. There are programs out there that duplicate the same content but make a few changes here and there. If Google catches you, and they're pretty good at catching this, you can kiss your page views goodbye.

Write your own content. That's as simple as it gets. Don't buy "instant AdSense" Web sites. If this really made lots of passive money, they wouldn't be selling them.

4. Add Keywords that Don't Relate to Your Content

Meta keywords aren't that important to Google anymore. However, when you list keywords, do list keywords that directly relate to your site, and don't repeat the same keyword multiple times. Spamming keywords by listing every word in the dictionary is a great way to have your ranking lowered in Google.

Likewise, don't use the trademarked names of products made by your competitors as keywords. At best it's a bad user experience, at worse it can get you sued by those competitors.

5. Link Exchanges and Bad Neighborhoods

Linking ordinarily would make you a good neighbor and a good citizen of the Internet. However, just because someone links to you does not obligate you to link back to them. Sometimes you do get judged on the quality of the friends you keep. Google calls spamming sites bad neighborhoods, and linking to them could lower your PageRank.

Link exchanging programs, paid link placement, and other schemes to manipulate PageRank are far worse sins. You may get away with it for a while, but eventually Google will catch onto the sceme, and your search results will drop like an anchor.  This is essentially what happened in the JC Penny's incident. The SEO firm they hired (and subsequently fired) created an artificial web of links.

6. Hide Text

Don't try to hide keywords by making the background color the same as the font color. This is called keyword stuffing or font matching. Google and other search engines are increasingly sophisticated at catching this, and they'll likely remove any offending Web sites from their search engine index.

Likewise, watch how small you make the text. In a variation of keyword stuffing, some people try to put teeny tiny text at the bottom of a page. It doesn't work.

7. Title Stacking

The old way people used to cheat on this was to add extra <title> tags to try and add more keywords into the very important <title> field. The new way people try to do this is by adding titles with dashes "Pie Crust Recipes - Cherry Pies - Apple Pies - Peach Pies."

That sort of titling system was highly recommended by SEOs for a while, now it's very out of favor and will probably lower your search engine ranking.

These days you're better off figuring out a clever title for social media sharing instead of using it as a way to stuff in extra keywords.

8. Doorway Pages

Doorway pages or Gateway pages are pages that are optimized for one key term but are really designed to be gateways to lead you to different content. For instance the "blueberry," "strawberry," and "orange" gateways might all be designed to get you to go to "fruit punch."

Doorway pages usually have very little in the way of original content and often cloak or redirect users to the intended Web site. Be aware of affiliate programs, because some of these may look like doorway pages to Google.

9. Automated Inquiries

Google doesn't appreciate robots writing your content, and they're even less appreciative of robots checking your ranking. Automated Google queries and automated link submission are both against Google's terms of service, and both of them can get your site banned. They tie up computing resources for everyone.

Source: http://google.about.com/od/searchengineoptimization/tp/badseo.htm