Grading Paper Money

Hi all,

I'm interested in which system are you using for grading paper money? There is so many of them. I find the IBNS system a bit vague.

For a practical question - is it possible for UNC or aUNC note to have small stains on it that are not visible right away? IBNS system mentions stains, smudges and dirt only for the VF note. Does this mean that if the note is otherwise perfect that it will be graded VF - XF at best if it has a small, not very visible stain according to this standard?

Based on PMG PAPER MONEY GRADING SCALE that is using 70-point numerical scale derived from the Sheldon numerical scale, UNC note can have these imperfections.