I think that Facebook has a social duty to set the bar in terms of what is acceptable to do with this wealth of user data. Never before has there been one place that has so much detailed information about so many people - with great power comes great responsibility. The rules are still being refined. Things get tried - some work, some don't - then from this, lessons are learnt.
I don't think there's a rigid bar to judge them by, though - nobody else has had this much data in one place before. There are best practices and things that one might deem "sensible" or "fair" but they're ultimately still trying to figure out just what to do with all this data.
Put it a different way - do you think anyone who works at Facebook would want people to think the company isn't trustworthy? I'd suggest not as it does nothing but harm the company. The decisions are likely made with the best intentions in mind, but to err is human and I don't think that Facebook have all the answers.
