Our office, in Yorkshire, geo-locates to various districts of London or Manchester and never actually where it is. My home is located 30 miles away from where Google thinks it is and today, in the East Midlands on the train from Leeds to London it has me located in Sweden.
This is a minor inconvenience for me but for some of our clients that use geo-location for advertising it must be really hurting them by showing totally inappropriate “localised” adverts.