EdgeRank analyzed Facebook hashtags by looking at more than 500 Pages in July. Within these Pages, there were more than 35,000 posts, of which more than 6,000 had hashtags. To get the metrics, EdgeRank averaged each Page’s performance with and without hashtags.
No matter how EdgeRank tallied the data — such as based on how many fans a user had, time of posting, and consistency of hashtag use — the Facebook hashtags did nothing for their users.
via Facebook hashtags said to have zero viral impact | Internet & Media – CNET News.
As my colleague Danny Olson points out, “I would imagine a very small percentage of Twitter users even click hashtags to see what else people are posting about on the subject, so for Facebook, which can only display public posts (a minority of site users), I would imagine this would be even smaller. Even more so since it’s not a native behavior to its platform.”
I personally forget to use hashtags on Facebook, even on my public posts. It’s just not an intuitive behavior on Facebook.