I've tried it. i don't use fb for pics. i don't use wifi on my smartphone and i had the fb app only briefly installed. i also weren't on any trips outside my city.

I've uploaded 4 screenshot-ed landscape (including one building) pics from flicker with absolutely no metadata. at least 2 of them should be very recognizable. the only thing that fb suggested was the single check-in that i had, minimum of 500km off.

i'm pretty sure that there is only minimal (if any) intelligence on image recognition and that they guess locations by information that "leak" from you and your hardware.