Ha! I once went to a Mansfield v Featherstone game which felt the same. I walked around the ground twice and everyone seemed to have come down from Fev and Mansfield scored to complete silence. Crowd was about 700 so there must have been someone from Mansfield there I guess.
Another one I went to was Trafford Borough v Hull KR, same deal. I walked all the way round Moss Lane and absolutely everybody was decked out in red & white. The only other contact I ever had with Trafford Borough was when the entire squad (all Kiwis, by the look of them) sat behind me at Old Trafford during the Widnes/Canberra game. They naffed off long before the end.
Trafford Borough was almost as daft an idea as Runcorn Highfield (but not quite as daft as Springfield Borough). Anyone who liked RL in Altrincham can get the bus to Warrington easily enough.