It will mostly get you deceived. People are rarely open in such way, unless they are of a certain personality type. Being open like this is really the worst thing you can do in the rel business world. Now, I'm not saying you shoe not be honest, but you should definitely plan ahead nd strategize before any meeting.
Though there is one shortcut to getting people to opening their mouths ( and thus give you an advamtge). Find a pain or a pleasure. They will regularly not shut up. But be very careful. Asking directly is not ideal. Make some research beforehand.