I think the most common example of this that we saw when looking was a fully finished basement and/or MIL. We saw lots of these listings: “Newly finished lower level with full MIL/second kitchen!!!”

We didn’t need a huge kids’ playroom, we didn’t want to rent out part of our home, and we certainly didn’t want our respective mothers-in-law coming to live with us… a laundry room, some extra storage space, and room for a workbench is all we wanted from a basement – and so it was all we were willing to pay for. We weren’t willing to pay sellers who saw it as fully finished and useable space (even when that’s exactly what it was, and to the right buyer, it would become a “unique commodity” worth playing hardball over), because we never would have used it that way ourselves.