That's how some of the greatest hacks in history have happened. Kevin Mitnick famous COSMOS hack came from his first manipulating his way into a telecom hub to steal manuals. Most major hacks start out with social manipulation or trickery of some kind.
That's how I got into my mother's Carbonite account after she passed away. I had access to her email accounts, cell phone, and a few key passwords. I played her and "forgot" my password and had a security code texted to her phone and then I reset her password and was in. I probably could have gotten a court order but didn't want to spend the money.
I made sure my sister knows that I have all my passwords on an external storage just in case.