When Another Agent's Clients Leave Me Messages Looking For Feedback

My message box is filling up with calls from clients of other agents. The sellers of homes that I have showed are very persistent at trying to reach me for feedback. I recently wrote about  "Sellers are calling before I even get out of the driveway..." 

I've been a licensed Realtor(R) for over 12 years now, and involved with it for a lot longer then that in other aspects. This tough buyers market has changed the way these sellers are acting. Or maybe these sellers doubt that their agent is doing their job. The internet has made so much information so readily available to everyone, so maybe these sellers read something, somewhere that makes them think they are helping their case by making these calls. When, instead, this action makes them appear more desperate then they even probably are.  

I have taken the time to call the agents of these sellers to let them know what I can tell them about the showing and also, that their client has left me a message. So, is that agent not communicating with their client? If they are, then why is their client trying to get feedback from me? How, ethically, can I call these sellers back so that I don't appear to be rudely ignoring them?