From what ive noticed going through other peoples post on diff forums, new delhi asks for passport when they are close to making a desicion and only the BC is left. In otherwords they are convinced that its a real marriage, which mitigates the need for an interview and barring any unforseen problems with the BC, one should get the visa in due time.
Now this is usually the case from New Delhi, ofcourse sometimes its different i.e people called for interview after their passport was received, or asked to get second police certifucate and such.
But yeah in my case they returned almost(not sure if all cuz i did send them close to 50 pics) all our wedding and other pics along with the PPR.