Questions for Buyers

We all have questions we ask our buyer clients before we begin working with them.  We screen because we need to focus our time and attention on those prospective purchasers who are truly ready to begin the home buying process.  An agent told me recently that he did not want to scare off buyers and felt he shouldn't ask so many questions at first contact besides are you pre-approved and for how much?  I feel that is a mistake; you really need to probe a bit further so you won't be wasting time.  I would rather know ahead of time of any stumbling blocks that may or may not occur down the road than simply start work only to realize later that your time has been wasted.