Marilyn Monroe was no fun to work with. She would report to work around 5:00 in the evening. You've been in make-up since 8:30 in the morning waiting for her.
I've always remembered something Sanford Meisner my acting teacher told us. When you create a character it's like making a chair except instead of making someting out of wood you make it out of yourself. That's the actor's craft - using yourself to create a character.