1script - 4:15 pm on Apr 11, 2013 (gmt 0)
Thanks for your input, guys. My concern was not so much about the links being no-follow as such but more about the cyclical nature of my acquiring them. It's pretty clear that any site would have tons of them, there's no argument here. Perhaps the way sites acquire them may have bearing but then, again, a site can be scraped overnight and acquire thousands of no-follow links from a scraper - is this kind of situation even a problem? I hope not. And looks like noone else reports the same issue, so I should look for other things that may be at play here.
As far as "illegitimate" no-follow links, in my mind that would be something that's automated like false pingbacks, those mass scraping operations I mentioned, almost any kind, really, other than manually posted in UGC on sites that automatically no-follow all UGC. In other words, something that should not even be a link in the first place. Or the exact opposite: something that should have been a proper link but you're denied the proper credit (usually the scraping falls into this category)