A fellow actor said to me "You have to go in as if you don't give an F***!" and he was on the right track. I think its important for us Creatives to remember that art is never complete. As actors and models we are definitely artists creating from our talents. So if its never complete and we can always do "better", why beat yourself up in the audition room. Live in the moment! On my vision wall I keep a sign that says "Show the director MY best version of the character". If you're living in the moment you are being yourself, even a very creative version of yourself. But don't put the pressure on yourself to be like someone else or be who you think the casting director wants to see. BE YOU and trust that you're talented enough to be Book It and leave the rest to the Universe.
I ended that question at workshop talking about negative energy that will sabotage you booking it. Between my Faith and reading "The Artists Way" and "The Secret" I know that what we think and say directs our path and can put the wrong energy out there. We can totally go against God's plan for us if we get in our thoughts so much that we feel we suck, we did horrible, we should've done this at the audition, and for sure when we look at the candidate next to us and start comparing.
Before auditions I'd pray this prayer and need to start doing it again, "God please let me be my very best self in this room and let me not be too hard on myself afterwards trusting that your Creativity flows through me". Try it out, see how your auditions and booking rate change when you change your mindset and live in the moment. This career is meant to be a fun one and life in general is meant to be enjoyable so quit making it so hard.