Pine, I'm not sure if I follow you entirely, but I too use images heavily, so let me tell you how I do it, and perhaps some of what I write, will help you.
Before I upload my images to Auctiva, I think ahead, and decide if I will need a new folder(s), of if I'm fine dumping the new images into an existing folder. If a new folder is needed, I create it, before I start image uploading.
Then, when I upload my images, I make sure the new folder is selected, so that the new images go directly into the new folder.
Then, I go create my listings, and hook up to the new images.
Now, when an item sells, and I want to get rid of the listing and it's images, I use Auctiva's new Listing Viewer (I think it's still considered beta), and from there I delete the auctiva listing. In doing so, you'll get a popup, asking if you want to also delete the associated images, and I tell it 'yes'. Thus, I don't have to hunt down these images I no longer need.
Bear in mind, when you delete a listing, and it's associated images, the Auctiva system is not fast. If you have a dozen images connected to a listing, Auctiva will spin for about a full minute or so, as it hunts down, and deletes the associated images. Even so, it's faster than hunting them down manually.
Hope some of this helps.....
Personally, I feel Auctiva's pricing structure for images is overpriced, so I use external hosting now.