What are they, or rather can you offer some examples? I'd be interested to see if there is consensus.

As I try to think of some, all I can imagine are situations where one entity might gain an (unfair?) advantage over another, or save itself some (deserved?) embarrassment.

If I put myself in the shoes of the entity that might gain, say "the authorities" catching "bad guys" through a sting operation or "the bad guys" dodging "the authorities" through secrecy, then I'd be tempted to support anonymity in the service of the goal. However, I'm very wary of ends-justifying-means arguments and if I try to step back from a particular viewpoint and take a big-picture neutral view then I rather like the notion of "all cards on the table" for everyone, all the time. Just a thought experiment.