Rust And Old Stamps

When an auction lot is described as having
rust that is when a lot will stand out to me.
These lots are usually very cheap and usually have
very little real rust at all. Some of the rustiest looking
stamps when cleaning them show that what looked like
rust is an old piece of paper or aged gum.

Many times I have said to myself that I will not be able
to clean this stamp because the rust is so bad and find
out it is a piece of old paper with gum and dust attached.

I wonder how others see this situation?