What makes a good hotel speaker?

The person setting up the room makes the speaker good it's all about setup unless you're jamming massive full range speakers into an overly tiny room.

I have never been to an audio show, but to me, your statement that the speakers in smaller rooms sound better makes sense. The set up probably has a more near field listening position, which means less interference to the sound from a bad room.

You need those bowls on the walls and tchotchkes all over the place :)

Agree the person's ears that set it up are key.

Constantly amazed by the ability of those setting up the systems and the stunning accomplishments made by some by the last day of the show. 

It is indeed set up and knowledge of rooms.  It's amazing how some exhibitors focus on cables and source but set up speakers improperly.  

If you walk in a hotel room and see a speaker being demoed right next to or up against a wall, know that this company knows little about acoustics.   These systems usually do not sound good unless they are extremely narrow dispersion, a trait that is usually the opposite of what you want for home use.  

Getting speakers away from the walls as far as possible is the first step.   Same for homes or studios!

Brad