Inbound Link Diversity and Google

[DavidM]

I had a thought. Sometimes people seem pretty picky about only seeing their links up among higher PR sites. Sometimes ignoring links from sites with lower PR. But wouldn't this be a way to detect possible spam? You would think that naturally a site with a truly high popularity would be linked to from a wide variety of urls at various PR levels.

Example:

50 PR6
100 PR5
500 PR4
1000 PR3
5000 PR2
7000 PR1
10000 PR0

This would seem natural as opposed to:

5,000 PR6
10,000 PR5
500 PR4
500 PR3
120 PR2
20 PR1
30 PR0

The second would seem an abnormality and point to manipulation. Would anyone venture to say that something like this is taken into account within the actual algorithm being used?
Any implications? The one I would suggest is that a more hands off approach (allowing for diversity) is probably safer for established sites.