De indexed by Google - unlikely reasons for the ultimate penalty.

If your site has been removed from Google's index; then, alongside another post on this site, Likely reasons for de-indexed; consider too some unlikely reasons for your site delisting.

• Selling links or engaging in link schemes.
• Linking to bad neighbourhoods.
• Hosting multiple sites on the same server.
• Duplicate content caused by standard site structure.
• Copyright issues without a DMCA notice in search results.
• Lack on nofollow tag on popular affiliate links
• Canonical issues
• Issues concerning H, H2 and H3 tags
• HTML Markup or non 'validation'
• Lack of alt text
• Lack of a favicon
• Capitalization issues in meta tags
• Text colour issues whilst text is generally viewable
• Lack of a privacy policy, terms and conditions and contact information.
• Benign duplicated data in /head area.
• Any issues regarding sitemaps
• Accessibility and navigation issues

These unlikely reasons have been drawn from submissions found in webmaster forums everywhere..