Small business owners. What's with all these calls to update our listings?

Once or twice a DAY now I get a call from some outfit I have never heard of before claiming that they just need to confirm all my business details are up to date. I just blow them off. I’m up to here with it. Google knows where I am. The Yellow Pages know where I am. The BBB knows where I am. Yet most of the time, these clowns claim they are updating one or more of these information resources.

What’s behind it? Is it just list building for spammers or something even more nefarious? Am I right to assume it is at best a total waste of my breath to give these people the time of day?