Depending on how devious you're prepared to be (Perhaps to prove a point?) it may be possible to be more subtle than that and send them well-formed rubbish? (as in, by modifying the hardware - the reverse engineering probably wouldn't be too bad if you had access to high speed logic analyzers etc.)
Then again, the manufacturer may program them to recognise that by making the device phone home with some kind of authentication.
Then again, the manufacturer may program them to recognise that by making the device phone home with some kind of authentication.