Walter Sanford has championed checklist systems for over 30 years. He has a time-saving checklist for everything you probably will ever do in real estate.
When you have commissioned buyer agents who do not produce leads (as you have), you will not get them to turn down a showing no matter how little information the buyer shares. If you have a salaried buyer's agent who handles showings and does the lead generation for secret properties, he or she will be more likely to do what you tell him or her.