Don’t forget that casting directors have seen everything.
Enter the casting room how it best suits you: in character, or not.
Maybe you work best always ‘in character.’ Then after the audition is finished you break out of character and say: ‘thanks for bringing me in,’ and then leave.
Maybe you need to go in as ‘you’ and say hello, suss out the room, hear what casting has to say and then do the audition.
It depends on you: the subjective factor, and on the role, show, day, casting, etc.: the objective factor.
You need to take both into account.
There aren’t any rules in acting, but there are lots of guidelines that you, in your practice, can use on any given day.
Which of your techniques or tricks will best serve you upon entering the room?
The audition room is your working space. It harkens back to the great amphitheatres in Greece. When in front of the camera you are in your place of work. It’s where you act.
Enter it in character or out of character.
Either way won’t determine whether or not you get cast.