Auditions. First impressions are important. If there is a representative or assistant in the lobby, they are not just there to help you out. They are taking notes and will pass them on to the Casting Director, Director, etc.
So if you are rude and don’t acknowledge them, that behavior does not go unnoticed. If you walk in without your sides or seem unprepared, that behavior does not go unnoticed. If you arrive late and full of excuses, yep, you guessed it, that behavior does not go unnoticed either.
Grab someone’s attention for the right reasons. Ultimately, you will be rewarded for being prepared, for being aware of others and for giving 150%.