First a note of clarification. There are two types of images which can be associated with caches:
1) Images embedded in a cache description
Although these images may include spoiler details, they are not considered spoilers. If you were viewing the cache web page on GC.com these images would automatically be displayed. These images are referenced in GPX files and as a result Geosphere can be set up to automatically preload them for use offline.
2) Images attached to the cache
These images may or may not be spoilers, but typically spoilers have the word "spoiler" in the title. On the GC.com webpage for the cache these would be shown as links. GC.com does not provide an official means to access these images meaning Geosphere will not be upgraded to provide direct access to these images. But there are indirect methods already supported...
Javascript
Cleaver programmers could utilize Geosphere's bookmark javascript capability to write a script to do most anything. But this does not help the majority so of users so I will not dwell on it.
Spoiler Sync
Geosphere already has the ability to import images and html files created by other programs such as Spoiler Sync http://www.anode.plus.com/spoilersync and attach those images to the corresponding cache. For those of you who aren't familiar with it, Spoiler Sync imports a GPX file and creates a folder with the spoiler images for all caches in the GPX file. Here are example steps you would follow to import these images:
1) Load a GPX file into Geosphere.
2) Load the same GPX file into Spoiler Sync and let it generate a folder of images.
3) Make a zip file from the resulting image folder.
4) Import this new zip file into Geosphere using the same technique you use to import GPX files.
I suggest the following Spoiler Sync settings (changing these setting is not a requirement):
-Shrink images to a height of 367 and a width of 320 (to keeps the files from being large).
-Uncheck the "Create web page for spoilers..." option (no need to import both jpeg and html files containing the same images).