My Bluetooth understands me for the most part, but it still sometimes dials the wrong number completely randomly. Like if I say "dial the wife", even though it clearly says "push the off hook switch to call 'the wife'...", it will randomly pick some other number in my phone to call.
It usually happens inconveniently, like when I was coming home in a storm at 2 a.m. and lightning struck the tree next to my house and my wife called me freaking out so hard that she disconnected the phone and my Bluetooth.... decides to call my sleeping boss.
Or the one time it randomly decided that "dad's cell" was an old booty call whose number I kept to block while my wife was in the car with me. Yeah. I don't use those effing keys anymore.