I got it to work !
OK, As several other have found, Bluetooth + A2DP +Pulse Audio + Mint 17 = not working.
I will refrain from repeating everything everyone else has written. in short, I have had to
a) edit my /etc/bluetooth/ audio.conf
b) use pactl load-module module-bluetooth-discover
and that worked, but not via A2DP, only via the telephony HFP/HCP protocol. But I found a way to get it to use A2DP.
c) remove the device
d) add the device using the command line not the Gnome GUI
$ hcitool scan
$ sudo bluez-simple-agent hci0 xx:xx:xx:xx:xx:xx (where xx:xx:xx etc is the address returned by the scan)
e) now restart pulseaudio & use pavucontrol to select A2DP (under configuration).
$ pulseaudio -k; pulseaudio --start
$ pactl load-module module-bluetooth-discover
$ pavucontrol &
And that finally actually caused it to use A2DP.
Step D was found at https://bbs.archlinux.org/viewtopic.php?id=157326
Hope that helps someone - Tom P, give it a try!
(full disclosure - I haven't rebooted, yet, so I will get the joy of discovering what is reqd on a new boot.)
I must echo Tom's frustration's though. It really shouldn't be this hard.