[DavidG]

Based on a comment on the auction website, itslow may have hit the nail on the head. Supposedly that's not remnant glue, but the original rubber pieces deteriorated to near liquid form. I have a couple of sets of those very limited reproductions, likely from the same batch, and they do not show any signs of deterioration, but who knows what adhesive was used in the case of those in this Victoria. (One would think that the seller would clean up the carpet or replace it before offering it for sale.)