The morality of gathering Facebook information

A recently story about HR reps requesting Facebook login credentials caused a bit of an uproar recently.  There's a lot that can be said about this, but here are some of my thoughts, focusing on why HR representatives may be tempted to gain that knowledge and then addressing why it is immoral for them to do so by requesting the login credentials.  I don't let the job candidates off the hook though, as I believer their sharing of the login credentials is also immoral.  Well... here are my brief thoughts.  What do you think?

Generally speaking, the more information we gather about a specific context, the more accurate our judgments in that context.  And the more information we gather about the other individual, the better we can evaluate their trustworthiness.  In business transactions, the establishment of trust is a major condition for trade.  To trade, information must be shared by both parties to establish trust.  In terms of privacy, this means that some personal information may have to be shared to establish a trusting relationship with our trading partners.  This is obviously context specific, as not all personal information is relevant.  Depending on the type of trade, however, different amounts of information may be required.  A security firm, for example, may want to much more detailed knowledge of their job candidates to ensure those potential employees do not violate the high levels of trust required for the job.  That's why some background checks require interviews of a job candidate's family and friends.  So I can make a case that under certain circumstances, a business may want to know how a person behaves on Facebook.  How they obtain that information however is another matter.

This sharing of information is often context specific.  People share information differently, sharing differing types of information and with differing expectations for confidentiality.   Unless it is established prior to the sharing of information, it is impossible to know what information others deem confidential.  On Facebook, it is impossible to know what posts by what people were shared with the expectation that ONLY their friends would see it.  If you indiscriminately share those posts with others, you may be violating a confidential communication.  Letting someone have your login credentials is unjust because you are gaining an unearned friendship.  You are not keeping potentially confidential communications private.  The HR rep is putting job candidates in an unjust position by asking for those login credentials.  They are directly challenging the integrity of the job candidate.