C'mon Man, Just Leave It Alone

Yes, but you can often spot that, as the corners on the trimmed note might then be too sharp for the grade of the note!

I have noticed that corners pick up wear very easily.
As an example, I have some spare UNC Irish notes that I kept from circulation since the 1990s - they were perfect when I kept them, obtained from blocks and carefully screened for 4 sharp corners [I have looked at lots of corners in my time, need a magnifyer now though - eyesight ain't what it used to be!].
On recent examination, the odd one amongst these has had a corner which has become knocked in storage. They might still grade as 64 (I have seen instances of Irish notes grades as 64 with one or more rounded corners) and are unused, but now AU-UNC imho.

-I suspect that's what happened to many of my notes (bumped/blunted corners) which I had bought as "Choice" (or better) but were certified later as "UNC60" by BCS. It was a serious let-down but I was the only one to blame for my minor handling (knocking my notes down in grades).

I just want to add re: washed/processed notes, that initially, these washings/pressed or processing DIDN'T bother me much. But later on, as the years passed, a pressed or altered note started to grate on me. After getting mostly fresh-pack UNC (see the vibrant hues & crispy clear under-prints) I began comparing side-by-side & my expectations began to shift (in a good way). I started to view altered notes (with fuzzy micro-prints or poor/thin lettering) far more cynically. It finally became a deal-breaker & I very rarely buy non "EPQ" (unless I know for certain that the note is indeed scarce in any grade).

But this level of discretion takes some time to acquire, or develop, to assess an Original "Q" note versus a processed specimen. It's a bit like grading in that it is an acquired skill (& eventually a taste) one acquires in order to sort out the "altered" from the "original."

I think your "Live & Learn" $100 National is an excellent example 'Steve' and thanks for posting & initiating this difficult topic.