Man in the middle attack!!
If that happens, get the mac address of his her android phone and blacklist it. Maybe if you pick a wrong one you can remove and try the next one you suspect.
Also, if he she is using phone as ip so that people can connect, so you as well can connect, but to catch him.
Get one of those wifi field survey apps like aruba or wifi signal strength scanner. Connect to this suspect rogue AP and start signal scanning moving towards where it is coming from.
I bet if he sees you moving towards the device point he she will run away, at least you will have a face.