Go to
ebay and find a good pic of a slabbed coin
with the red label and "CLEANED" listed on it.
Save the pic to your PC.
Now find the same coin, slabbed by the same company,
in the same detail grade if possible...
with the nice light colored label without the big, bold "CLEANED"
on it...
Save it to your PC.
Now either combine the pics and print them off as one comparison,
or email them to her.
That will show that it does matter to value, and the
big red label shows how ill we collectors treat cleaned coins.
Either that, or email her a direct link to this thread!