I recently added a Jupyter notebook to this repo to help people more easily test this code on their own local MAC addresses.
I'd be interested to hear what you find when running this notebook (called
localize_from_nearby_wifi.ipynb). For me, I found that, of all the MAC addresses my wifi interface could see, only one of them was in the database, but had three records, two in SF and one in Oakland, putting my estimated location somewhere in the middle of the SF bay.