Source: http://www.free-seo-news.com/newsletter712.htm#facts
Google’s Spam Checklist
When a website is seen as low-quality, this does not necessarily mean it is a spam site.
So when does Google see a website as a spam site? This checklist will give you an insight.
1. Your pages deceive visitors. If you have one or more pages that are designed trick search engines,
your site will be seen as a spam.
Examples of deceptive pages are:
* Sites with false product testimonials
* Websites that provide surveys to steal personal information
* Sites that claim to be a celebrity’s website but are made to collect money
2. You have malicious pages. If you have pages that are designed to get users’ bank account information, credit card information and other personal information, these pages are spam pages.
3. Sneaky redirects. Redirects that go to unrelated and shopping sites through affiliate links can be seen as spam pages.
4. You have no real content. If your site has too little or no helpful content, or if your pages
contain keyword stuffing or meaningless content, your site will be considered a spam site.
Auto-generated content is also not recommended for websites.