that is no different that stashing a mic in the room. if you actors are moving and turning their head around, this is not going to work for you, also, stashing a mic is used when all other means of miking this sceen have failed.
put a mic in your room and do a test now. turn in all directions move around, even bump it, like the actors will more than likely do. i do not think you are going to like what you hear.