I remember attending ACL one year, where the conference organisers ran an experiment to test the effectiveness of double blind reviews. They asked reviewers to identify the institution that submitted the anonymised paper. Roughly 50% of reviewers were able to correctly identify the institutions. I think there was a double digit percentage of being able to predict authors.

The organisers then made the argument that double blind was working because 50% of papers were not identified correctly! I was amazed that even with strong evidence that double blind was not working, the organisers were still able to convince themselves to continue with business as usual.