|You can check where your apt installed your package using
$ dpkg -L bluez
Note that if you're querying packages, you don't need to sudo to execute dpkg. Also note that the normal package for bluez does not include libbluetooth. For that you need packages libbluetooth3 and libbluetooth-dev (for headers, etc).
$ dpkg -L bluez | grep libbluetooth.so
$ dpkg -L libbluetooth3 | grep libbluetooth.so
$ dpkg -L libbluetooth-dev | grep libbluetooth.so
I expect if you've built these packages for armhf and installed them on your X86 sytem, then they may not be in the locations listed here.