I use a justhost.com reseller account to host about 15-20 of my own websites. None of the sites are related, nor do I interlink or do anything blackhat with any of them. All of the sites have unique content. Some of it isn't great, but I didn't use a writing service on any of then, it was all written by myself.
Recently I found a list of my sites (as well as about 200 others hosted by justhost) on a hacker website that listed the cpanel usernames. I alerted the host and the issue is being fixed. I am changing all of my usernames and passwords for all of the sites.
Anyway, I recently took a look at some analytics and rankings and noticed that I lost a lot of my rankings on a handful of those sites recently. I know there was the big de-indexing of junk blogs recently, but I don't think that is the case. I can still find all of my sites in Google, they are just out of the first 50 results, when a majority of them were ranked from 5-20 in the SERPs.
Here are three of the sites and their phrases:
http://nintendoconsoles.com/ "nintendo consoles" - This domain I bought from someone so there could be some sort of sandbox period for it.
http://webhostingfordrupal.com/ "web hosting for drupal" - This was a new register.
http://seotirical.com "seotirical" - we don't show up, but all of the tweets and links to us do. - This was a new register.
I realize these sites aren't perfect, and might not have been ready for the first page. The Nintendo site is about 3 months old, but the Drupal site has been around for 8+ months. I might try adding a fresh piece of content tonight to see if that helps, but I thought it was curious that it happened across the board with about 5-6 sites on my one reseller account. I don't even know if the top portion of this post has anything to do with the problems, but I thought I'd see if anyone has insight.
Cheers,
Vinnie