SEO Thoughts
Google seems to apply the -30 filter to web sites that use spammy SEO methods. If Google finds out that your web site uses invisible text, JavaScript redirects, doorway pages or similar spam techniques then your rankings will drop by 30 spots.
The Google bomb filter seems to be applied to web sites that get too many identical links in a short time period. If a web site gets many links with exactly the same link text then Google will downrank the page because such an unnatural linking behavior indicates a manipulation attempt.
Six reasons why search engines ignore your web pages
I got an interesting article from Axandra newsletter which list down why search engine ignore your web site, even you have submitted it. If you are still wandering why your site is not listed on search engines check out following reasons
1. Check if search engines can read your web page content
2. Check if search engines can find your web pages
3. Check if your web server causes problems
4. Check if your web page content makes sense to search engines
5. Check if your web site has the right inbound links
6. Check if your web pages contain spam elements