The Google Home devices only keep 1 second of listening when they are not active (by saying 'OK Google' or 'Hey Google'). That second is constantly rewritten. There is also a physical mic on/off switch on each device which will disable listening completely.These types of speakers are going to be very common place in homes, and I think the expectation will be that they will be available in hotel rooms. I think Disney is wise to test this out - privacy will of course be a big issue however. It should be easy enough to offer a way to opt out - either power off or remove from the room.
Echo devices work much the same way - constant 1 second recording which is rewritten - but the chances of a word sounding like 'Alexa' are a lot more common than the Google wake words (mostly because its two words). There are definitely cases where it records things you wouldn't want it to, but these are fringe cases and not a normal occurrence. Changing the Echo wake word (other options are Amazon, Echo, and Computer (for the ST:TNG fans)) will also cut down on the accidental activations since those words don't sound like many other words. Most Echo devices do not have a physical on/off mic switch, however.