It's taken me close to a year with my current system to have it set up right. I don't care how much you spend on a system. It will take months to reach it's full potential...tweaking the room, components and cables, isolation, ect.
Exactly, so people should cut the exhibitors a break! Exhibitors certainly do try. Also, many make a judgement based on one day. The equipment may be new (one would be shocked just how often this is the case), something may be on the fritz from shipping, room acoustics, something got lost, etc. You just don't know. Usually, unless something sounds amazing out of the gate, I don't "judge" any room until Sunday.
Another consideration is that exhibitors combine resources to pay for a room and they don't know how things will sound until they arrive. Right or wrong, that is the economic reality.
But I understand most attendees don't have the time. And neither do I sometimes and miss things too.