red_bus wrote:
Agree with Mike that it depends upon the amount of staple rust.  

The sad truth is that staples can rust fast even in sealed box sets. I remember opening about four sealed chaosium box sets in a row all of which has staple rust on the booklets.  It is really common.  The only thing which would guarantee zero rust inside a sealed box set would be if there was a desiccant placed inside before it was sealed (i.e. like they often do with electrical equipment).  As to storage, I am not an chemist - but I would think that storage in a place where temperature changes are significant - probably accelerates this process.