We run a social-news site (like DIGG). Users submit stories; other users rank them and comment on them. The stories with the most votes appear on the homepage.
How much policing (or censorship) should we do to avoid linking to "bad neighborhoods"?
We suffered an attack by pill-spammers earlier this year; spammers submitted hundreds of pill-spam URLs with headlines like "buy viagra cheap" and so on. We ended up being pretty highly ranked for related terms. We deleted all such stories, because they're not news and because we feared repercussions of hosting hundreds of links to spam sites.
Adam Lasnik of Google said (here on WebmasterWorld) "our algorithms are tuned to look for patterns of 'egregious' linking behavior." Is it possible that user-generated content, including user-submitted links, could constitute a "pattern of egregious linking behavior"?
Is the simple answer to nofollow all those user-submitted links?
The problem with nofollow is that it would eliminate all of the outbound links from this section of the site, 99% of which are to reputable news websites. I don't want to lose all the good links out of fear that a small percentage of bad links will cause damage to our reputation and rankings.
If you cannot be sure that moderation will catch all 'bad links' quickly and effectively, then 'nofollow' is entirely appropriate and very effective.
In fact, that's what it was designed for; you are deemed to be responsible for your outgoing links - SEs assume that if you have placed a link, then you are recommending the ste. With third parties having access to your pages, then without tight moderation, you may find yourself recommending all manner of sites. :)
Digg doesn't use nofollow. Granted, they have 10x as many sitewide backlinks as we do, and may therefore be given more leeway by the algo than we would be. Meaning, they have more authority. (Do we have any public metrics to estimate trustrank?)
I've seen other user-generated news/content sites that DO use nofollow, and I understand that that's what it was designed for.
Still, I'm wary of turning off (via nofollow) all the *good* links to real news sites, which might rob our site of any reputation it might have earned as a hub. Perhaps we can use nofollow on new story submissions, and drop the nofollow after a story has earned sufficient points/comments.