Oh...right. Misunderstood.
I use "
Enhanced Media Library" plugin to make categories. All my logos and site related pics go into SITE category. All blog pics go into BLOG category etc. All product images are uncategorised.
Then when a product is deleted (and the Products Trash is emptied) ... I filter the Media library for "Not in a Media Category" and "Unattached". The only pics displayed after that are from deleted products. I then select all of them and delete them.