I use a $3 ebay bluetooth dongle with torque - works great for me and my Grand Marquis, but I have had issues with GM vehicles' ECUs not communicating (mid-00's Grand Am/Prix). After loading the custom Ford PID's (basically the ID/Parameter for reading OE specific sensors/codes) to Torque Pro (about $6 on Play store) I can see a large amount of information from within the ECU - it even allows me to see things like specific cylinder misfire counts, which is useful because Ford decided that it shouldn't throw a code unless a cylinder is misfiring something like 23.5% of the time. I love my cheap torque/BT dongle combo for what it is.
HOWEVER, they certainly don't work for every vehicle (at least the cheap $3 clear-blue china units) and then there's the issue of it only communicating with the ECU. That's fine and dandy if all you want is to check/clear basic codes - it works great for that, but if you want to talk to the TCU or ABS system, you will need a dedicated tool. My 10yr old Harbor Freight scanner can read TCU and ABS on my brother's Kia.