Marketers have lauded Pinterest for its “stickiness,” its ability to keep people on the site. Pinterest is so addictive, in fact, that it may be hurting referral traffic.

When it comes to engagement, Pinterest is powerful. According to studies done in early 2012, visitors are likely to stay on Pinterest for more than an hour per month on average—longer than the time spent on Twitter or Tumblr. The image-sharing network still hasn’t surpassed Facebook, but it’s far closer than it was in February.

While traffic to Pinterest is significant, traffic coming out of Pinterest is lacking.

According to Pinterest statistic tracker Repinly, PBS is the most engaging news outlet on the entire network. Yet, in an interview with Poynter, PBS Director of Digital Marketing Kevin Dando said referrals from Pinterest to the PBS site are “not yet a realistic goal.”

“We know the clickthroughs will come and the way to get them is through engagement,” he told them.

But this could just be optimism speaking. Across the board, the outlets Poynter spoke to all shared similar concerns about traffic.

“It’s not a driver of clicks at all,” Denver Post’s Daniel Schneider told Poynter.

It’s not just news-related pins, either. Even Pinterest’s top traffic driver, Etsy, struggles to get back what it puts in to Pinterest. Though Etsy is the largest source of traffic going to Pinterest, outranking even Google and Amazon, the handmade marketplace still has trouble getting users to click through, as indicated by its latest, intensive Pinterest campaign.

We’ve long suspected that Pinterest may not be the traffic driver some claim it to be. In February, a Shareholic study that indicated Pinterest to be a stronger traffic driver than Reddit was debunked by Reddit data. The study, which relied on Shareholic’s social-sharing tool, took only its own numbers into account. (A more accurate title for the study would have been “Pinterest is a stronger traffic driver for Shareholic users.”)

Social-media marketers still believe Pinterest will one day feed its massive amounts of traffic to their websites and blogs. What else could explain why there are 182 results on Amazon for books on marketing with Pinterest? But for now, even top engagers are having trouble making it happen.

Photo via Alan Stanton