Sometimes, an orchestra director chooses to acknowledge an issue with his players passively instead of harping on it. (Yes, it happens sometimes.) My high school orchestra always knew when the director was unhappy with the class's playing but didn't want to dwell on it.
"Goooooing onnnnn...," he'd say, elongating the syllables to let us know he heard our miscues. Other times, at the end of a movement the class hadn't played well, he'd say, "Pitch that, and go to (the name of the next movement, piece, or composer.)"
Sometimes, that's the best approach for a director to take with an orchestra. Acknowledge indirectly that you heard the musicians' mistakes, infer that more practice is needed without saying it, and then, go on to the next movement or piece.
