I'm the same way, I don't like rusty staples on a high grade book
Thats one of the reasons why I always buy graders notes for slabbed books. I've had a few times where I stopped a definite purchase because of notes disclosing rust.
That's extremely smart to do, especially for a high dollar book. I remember back in the day, I would call in to CGC to get grader's notes for "free" and talk to Steve Borock or Mark Haspel on the phone as they discussed all the notations and defects on a particular book. They would even tell me what the primary grader, secondary grader and final grader's individual scores were on a copy