I want to give the audience a hint of a scene. No more than that. Give them too much and they won't contribute anything themselves. Give them just a suggestion and you get them working with you. That's what gives the theater meaning: when it becomes a social act.
The virtue of dress rehearsals is that they are a free show for a select group of artists and friends of the author, and where for one unique evening the audience is almost expurgated of idiots.