If you need these images, then don't run the Addon cleanup - but anyways they would be downloaded again, so they can be considered cache files. These include some that might actually be useful like 'ArtistSlideshow' that collects a lot of images.
There are 9 addons which are cleaned, I tried to find ones that collect the most garbage, temporary files, or just a lot of files over time.
Even now it cleans some addons that tend to collect huge caches, that no other cleaning addon cleans! Now, mind you, this is only release 0.2, but more features will be added. And then I decided to write my own, and add a few things no other cleaning addon has. So I ended up using 3 different cleaning addons. Some are not maintained and all functions don't work. There are a few cleaning addons, but none clean everything.