I often see threads at the Google Webmasters Help discussion forum of people who have sites that were penalized for having issues with their site in the Google Webmaster guidelines. But it is not often where you see a thread that one issue then opens up an other issue, then an other issue and so on.
Then I see this from the webmaster:
My partner's brother had muscular dystrophy. He made several md sites based on personal knowledge as well as medical facts. These are examples of our sites which are useful and deserve to be indexed.
We have hundreds of sites like this.
Okay, to have hundreds of sites in different topics make sense. But to have hundreds of sites on exactly the same topic? Well, that just seems redundant to me.
In any event, the thread is an interesting read in that this webmaster is getting advice from both SEOs and Googlers on several layers of issues.
Forum discussion at Google Webmasters Help.