Does anyone have any idea who to contact about the Facebook link preview crawler (user agent http://www.facebook.com/externalhit_uatext.php)? It's constantly making requests to our site in what seems to be a loop of sorts. Things have gotten bad enough that I've had to rate limit it! At the rate things are going, I'm sure it's blocking legitimate requests for previews of links on our site.
I've started rate limiting the crawler. I'll report back and see what kind of effect that has on us. I'm also going to look into whether or not temporarily disabling ads has any effect.
Disabling ads had no effect!
We're having the same issue. We started using Facebook Ads a few months ago, so I'm suspicious about the connection.