lucy24 - 7:10 am on Oct 29, 2012 (gmt 0)
I've just returned from what I thought would be a quick detour to logs to see just what pinterest looks like in action.
As luck would have it, the only recent pin I could find was a jpg blowup that opens directly from a gallery page. So dozens of extraneous hits to plow through.
Narrative as extracted from logs: Human does a g### search (naturally no clue what she was searching for) and lands on this picture associated with the page. As an alterative to rushing out and telling her eighteen closest friends, she first runs over and puts the picture on Facebook, and then turns to pinterest. And then there's some business with tumblr.com that's so much Hungarian to me.
The thing is: I cannot for the life of me figure out how pinterest gets hold of the picture. It isn't hotlinked. They keep it in their own archives. You may think Well, that's something at least. Actually it's bad, because it means you have no control over whether they continue to show your picture. I have to assume they made the pinner do their shopping for them, because there are no unaccounted-for visits. It's all the same human. One of them gives pinterest as referer-- but that's just the user testing her link.
I know because I tried the same link and got the same referer. You can follow it in the other direction and see the page you're pinned on. This time around, the only extra was a preliminary attempt at a HEAD on my page. I say "attempt" at because it was from an Amazon AWS range. Under-the-radar type of UA:
"Mozilla/5.0 (Windows; U; MSIE 9.0; Windows NT 9.0 [really]; en-US)"
Yawn. No idea of course what would have happened if they hadn't been blocked. The page doesn't say anything like "We couldn't get through, so we can't promise the link is still valid."
They seem to have a little more confidence in their members' judgement, because there's no intervening "Danger! You are leaving Pinterest!" page.
Conclusion: As far as I can tell, it is impossible to prevent your material from being pinned. The only thing you can detect is pinterest in the referer-- and those are the very ones you don't want to block, because they're real humans heading your way.