I recall a few years ago being able to create really meanifull and helpfull queries on facebook like:
Friends of friends who like mountain biking and live in New Zealand
However it seems that facebook's search has been dumbed down. Were the searches too computationally intensive or abused in some form?
Any FB employees care to chime in as to what happened?
I believe the story is that they shipped it, and then found that the people who were using the most powerful parts the most weren't exactly the kind of customers they wanted.
Since then they have been modifying the API so less and less of it works. It is very difficult to work out exactly what and what doesn't work because it depends on the the account you are using and that account's relationships with the people and groups you are searching, as well as the rights each of those gives. The FB default permission schemes have changed significantly over time (to be less open) too.
Also, there seem to be bugs, and it is difficult to know what is intentional, what is because of permissions and what is a bug.
For example, it seems impossible to read posts made by other users to a page via the graph API even when that same account can read them when logged in interactively. This doesn't seem to be documented anywhere, and there are plenty of online sources showing code that seemed to have worked previously. So is it a bug or deliberate? Most seem to assume it is deliberate, but who really knows?
To be clear: I have no internal FB sources on this.