How to sniff Bluetooth traffic using Android?

I'm not aware of something that would turn your Android bluetooth radio into a sniffer. I think you would need to invest in an Ubertooth to accomplish what you're looking for.

http://ubertooth.sourceforge.net/ http://hakshop.myshopify.com/products/ubertooth-one

With the ubertooth you'll be able to sniff the bluetooth packets between your arduino devices.