I'm always surprised that there are so many people that post here...who claim to know so much about the theatre, but know so little about the process.
Indeed, previews are nothing more than rehearsals that the audience pays to see. Whether they should be charged less for viewing them is another argument all together. But anyone who buys a preview ticket for anything, should be prepared for tech tables in the audience, directors dictating their notes to his or her assistant, designers on computers making adjustments to lighting and sound cues, and flashlights or computers screens going on and off.
Not every adjustment can be made during a closed rehearsal, sometimes it's necessary to have an audience in the house. This is especially true when it comes to sound design. A full house eats up the sound, what sounds perfectly audible in an empty theatre can be muffled and inaudible when every seat is full.
Previews should be advertised as such...and if you don't understand what a preview is...then you shouldn't purchase a ticket for one. Previews are there to benefit the play the designers, director and the actors...not the audience. If you are unhappy with some of the technical aspects of show after it opens...imagine how unhappy you would be if the designers and directors were unable to do their work during the preview period.
"Just a Guy. Your feelings are touching. I am gladdened by the thought that you will one day wind up 6 feet under as we all do." - MrRoxy ------
"I do not suggest you walk out the door onto a New York street with your vulnerable child part exposed and not protected..." - Jason Bennett