Understanding Google kinds of ban

Sometimes ban is just having PR0?

[fischermx]

I am reading an old word document that supposedly describe the way Google train their human reviewers of SERP to distinguish between good site and spam.
In one of their examples, they mention a DMOZ clone, a deustch site, where was supposedly marked as spam.
However, the site :
- Show inbound links for link:example.com
- Show indexed pages for site:example.com

The only "ban" signal I see is that it does not have any PR.

Now, I have some sites, with original good content, that does not have PR, have 0 pages indexed and show 0 inbound links eventhough they have dozens. They have been like that for months.
The only sin of these sites is that they were expired domains that I catched in drop services.

If a site marked as "spam", still being indexed and showing backlinks ... what kind of hell of ban does my websites have?