I think limiting the number would help, but spammers will spam, and you are still making it really easy for them to do it. You could also try to tighten up your algorithm so you give fewer false positives, but I'm sure you'd eliminate some that really are related if you did that.

The real solution is something you probably don't want to do. You should provide a list of possibly related links, but no automated way to put them (or copy them) into the post. A blogger would actually have to click on the link to see the article and copy the url to create their link to it. That would virtually eliminate the spam. People would only use your related links if they really wanted to and were thinking about it. If that were the way it worked, I might even turn Zemanta back on myself, but right now I'm so fed up with spamming pingbacks that I don't have it on anymore.

I do really appreciate your response....

I must agree that there are some users that use our service recklessly really actually clicking everything away like it might do some good for their blog. We really don't like when they do that, though. But we haven't found a good way handle them. Maybe having a limited number of related articles would do. What do you think?
We also keep improving our recommendation engine and the user experience so the user knows what exactly he's linking to. But some chose to ignore that.
We know that WordPress itself has issues with spammy pingbacks but it seems we are facing the same issues.

Hope this helps.

Best,
Rok from Zemanta

I get pingbacks, usually multiple times a day (just got another), from people who have obviously used Zemanta to generate a massive long list of related links on their post. I look at their post, and they haven't interacted with anything I've written, and often the connection is tenuous at best. Sometimes, it is a racing certainty that they haven't even read what I've written, because Zemanta was stupid, and what I've written has absolutely nothing to do with what they are talking about. Yet there is the link, and here is the pingback in my pending comments.

I've decided these pingbacks are spam, and I trash them. Pretty much the only time I let a pingback stand is if someone specifically interacted with my post. The exception would be if their post is closely related to mine, and they only have a few "related links" -- indicating that they've actually looked and pared down the list to those that they might actually want their readers to see. Then, I'll usually let it stand.

So, what do others think? Am I right that this is a form of spam, or am I out to lunch?