Many times directors give notes that are entirely undiscerning or unplayable. Directors are thinking about the play differently than the actors, stage manager or designer - they are seeing the whole picture. And sometimes this translates to getting a note that refers to something that the actor knows nothing about. Or it could be that the director gives a note that is really a signifier or a metaphor and not a real action or emotion that an actor can play. Sometimes the director is second guessing his or herself. Sometimes that person just doesn't know what they are talking about. Many times, they are responding to what they have just seen before them, having a very strong emotional or intellectual response, but haven't had time to really sort through their thoughts so that what comes out of their mouth is a complete mish-mosh of words and ideas.
I am as guilty of this as anyone - more so at times.
The trick is not to take yourself too seriously and really take the time to stop and listed to an actor's question if they need clarification. Take a moment to get your thoughts together before you speak.
Humor also helps. Making fun or yourself makes the actors know that you are not being too pretentious and expecting them to understand every single world that flops out of your mouth (an subsequently dies).
One of my favorite notes to give in this case is "the scene needs more FISH." It's a joke me and a buddy have. We both know it means nothing and soon the cast realizes this (though they are often confused at first). But the more it is used throughout the process, the more it helps as a stress relief later.
There is another actor, who is a very close friend of mine, who I will often give then note "could you please suck less" or "just take the suck out." I know I can give the note to him because not only is he a competent actor who is very much on top of his process, he is also a confident person and can take the joke (and he knows that I am only joking). I would never do this to an actor who was less confident or struggling in their role.
Just some rehearsal room humor to keep the mood light and to let them know that their director doesn't care if you make fun of him too.
John Howard Payne (1791-1852)
J.M. Barrie (1860-1937)
Cole Porter (1891-1964)
George Axelrod (1922-2003)