I suppose it is possible. But, if no serial numbers are listed, and contact for the actual sale is made with a telephone, it does not appear that they gain much, if anything.
They could determine who advertised a gun for sale - but that it legal, and after the sale, the gun would not be there.
“that it” should be “that is”.
What if the BATFags are the webmasters, and are busy collecting and mining data?
You take a chance listing guns anywhere, even reputable sites like ar15.com have unsavory characters lurking. This is no different.