Anyone can collect information about bluetooth devices on the go, and with simple Tooting action you could try to force the user install malicious software on his device.
But whats the point of all this ?? In the end you gain not much, except for maybe a list of personal contacts which you can use for complete psychopate experiences.
You dont need an array of devices to see if a certain exploid is working, just get your hands on the device implementation docs or just start cracking your own device ;).
On an average train journey I discover 10/15 Bluetooth enabled devices on my Mobile.
Using the same Mobile, I also discover 200/240 WiFi Access-Points with zero encryption if I travel by car.
The latter at least gains enough connectivity to browse 'Slashdot'.
Trying each door to see if a car is locked, is pointless unless your trying to steal it.