It's impossible to make 100 percent BT dongles working in Android, like happens with 3g dongles, no matter device it's an ainol, s7300 or nexus. Android has a limited compatibilty, like Linux, if dongle is hci compliant and Linux friendly should work, if not, obviously won't work.
I have BT added for the GPD 5005, compiling from Google AOSP source, but I am conscious that not all dongles will work. Same for s7300 I imagine.