I haven't been to tons of shows, but I've done Axpona twice, RMAF once, and most recently last year's Capital Audio Fest. Each show venue is different, but each offers entertainment and a great deal of education if you limit evaluations to things you can hear a difference with. The best expectation is to have fun, learn about a product type you may be considering (headphones, ultrasonic cleaners, room correction, music servers, etc) and maybe buy some music or accessories.
If you go to a show to hear speaker XYZ hoping to be really impressed, don't write it off if it sucks at the show. I absolutely love my speakers despite less than good initial exposure to them. I did hear the qualities I was looking for and knew they would do better in my room.
Most rooms won't come close to your room, not by a long shot so everything you may actually like will sound different at home, usually better unless you have a challenged room.
Managing crowds so that people can year things at their best is also nearly impossible. There are limited speaker types (Omni) and setups that accommodate people all over the room, both standing and sitting. Many systems need their sweet spot for best sound. How many of us have entered rooms where getting the sweet spot just isn't worth the wait?
You just need to know shows won't give you all the answers.