I've had just a mild paranoia about someone using Alexa to eavesdrop on my conversations at home. Only mild, though, as I can't think of anything in my conversations with either my wife or my dog (yep, I talk to my dog) that I'd be particularly nervous about anyone hearing. But inaudible commands embedded in music might cause me incredible grief (see the UK Register article here).
Not only could my Alexa device make unwanted purchases from Amazon—who cares whether or not I get free shipping on a walk-in bathtub?—but I'd hate to see my bank account drained just because somebody hijacks an Oldies But Goodies music commercial and puts secret commands into the soundtrack.
So, ah, Dear Amazon, Google, Samsung and Apple: You might want to put frequency filters in your voice-recognition devices. Thank you very much.