While there probably is detailed testing like you describe going on, I think it's reasonable for an exec to check out the competition at a show.
However, if the show has not yet started, then probably nothing gives the competitor the right to do so.
Frankly, I think the show venue should not allow such testing of machines that are being setup on display,
without permission.
No entering another vendor's booth without their permission and supervision.
So the charge should be trespassing.
There's nothing that says the products on display necessarily have to be done yet and 'fit' for normal use.
The competitor has no permission to 'operate' the equipment, no manuals, etc,
so touching it at all could be deemed as potential abuse.
Being curious and testing shouldn't be considered as malicious vandalism,
as long as its supervised and being tested only to the extent intended by the vendor.