Find my iPhone can "online, location services turned off" show if someone has not turned off location services manually? Can "online, location services turned off" show if someone has not turned off location services manually? Is there any time that the location is unidentifiable, such as in a downtown area where GPS signals are not reliable?
If location services are enabled and the location can't be obtained by the device because there's no GPS, etc, it will say so: 'location unavailable'.

The fact that it says the location services are off means literally that: the location services have been switched off.