There is a bit of an arms race between get a few $/c extra CPM by spoofing the geo location (the app needs to ask for this, and have reason to from App Store pe

There is a bit of an arms race between get a few $/c extra CPM by spoofing the geo location (the app needs to ask for this, and have reason to from App Store perspective, so not always available), and the data aggregators detecting said spoofing (all clients having the same geo / patterns in geo etc). Reverse engineering will get you a PoC, but you can buy the cleansed data fairly easily (apparently..)