We all bow down to the gods of traffic, but the reality is that not all traffic is created equal. Perhaps if you’re selling junk page views to an ad network for rock-bottom prices, it’s all the same, but for most pages on most “quality” content sites, some kinds of traffic are definitely better than others.

Digg and other social news sites have captured the imagination of publishers because of the massive amounts of referral traffic that Digg in particular can drive, leading to the obvious comparisons to Google and search engine traffic. Danny Sullivan points out that, in terms of raw traffic, sites like Digg seem to beat out non-Google search engines. (TechCrunch’s referral sources was an important reference point.)

But mounting evidence suggests that Digg traffic in particular is less like networking with like-minded individuals at a social event and more like getting attacked by a pack of wild dogs, who leave nothing of value in their wake, other than lessons learned on closing comments and crashed servers.

SiteLogic has a great, detailed analysis of how traffic from different sources behaves on three different sites. The third analysis, of Kim Kraus Berg’s CRE8PC, has specific data on Digg vs. Del.icio.us vs. link traffic vs. search traffic. The difference is striking.

Digg referrals spent an average of 3.6 seconds on the site, compared to link referrals that spend an average of one minute or more. Search and Del.icio.us traffic don’t spend much time, but Digg’s average is only 25-50% of the other averages.

Kim herself wrote a post titled “I Don’t Digg Being Dugg”, where she observes what many others have –Digg users are abusive and generally uncivilized:

Another way of looking at it is this. You take a walk through a park and quietly enjoy it and the experience. Perhaps you will recommend it to someone else. Or, you can visit the park and leave graffiti all over the benches, paths, and toss toilet paper into the tree branches.

Many sites, including the New York Times, have put “submit to Digg” buttons on their content pages, figuring that they need to bow down to the traffic gods like everyone else. But it appears that the Digg traffic god is not a benevolent god.

At some point sites are going to start to discriminate among traffic sources in terms of quality rather than quantity. Sure, if you have advertisers who are willing to blindly monetize any page view, it might not seem to matter on the surface. But I wouldn’t count on that lack of discrimination to last.