Realtors: real or fake?

I have not sent out any neighborhood flyers for my listing at 3031 N. Lamer in Burbank, nor have I gone door to door in the neighborhood to promote it. (I'm using electronic marketing, obviously.)  Imagine my surprise when a neighbor told me that "the listing agents" had knocked on the door recently and asked to come in.  The neighbors say this couple was very professional, but insisted on looking at the entry to the house, the flooring, etc. for "comparison." They even had a flyer.  No, the neighbors didn't keep the flyer. 

I don't know anything about this and don't know who this could possibly have been, and I'm suspicious.  Sure, some Realtors go door-to-door, but you'd think I'd know about it if they were advertising my listing.  Were the couple really Realtors, or were they using that excuse to gain admittance for nefarious purposes? Yes, I called the Burbank PD watch commander.  Keep your doors locked during the day, folks.