Content_ed - 8:02 pm on Dec 5, 2011 (gmt 0)
I noticed something for thie first time today that I might have missed if you hadn't mentioned page areas. I was filing DMCA complaints for a moderately long page of mine, and as I went through it picking a unique phrase from each paragraph to check, my page blinked in and out of the Google results. When it was out, not even the "show additional results that are similar" brought it up.
The difference was this. The phrases for which my page failed to appear were phrases from paragraphs that had been copied into relatively short articles that were then syndicated! And due to the fact that only a few scattered paragraphs on my page were deemed juicy enough for the particular black hat link building effort, the result is that on a single page of mine, there are sections for which Google considers me the undisputed source, and sections for which they think the page does't even rate a second chance appearance.
In, out, in, out. Firt time I ever noticed that for a single page.