Do you have older items in your Poser / DAZ runtimes, which have no thumbnail previews? The free RSR to PNG Converter will scamper through your runtime and make a .PNG thumbnail for every non-thumbnailed Poser .RSR file that it finds. Still works fine in Windows 8.1, and is a nice addon for PzDB.
Load | then point at your ../runtime (not your ../content); select ‘recursive’ | let it run (there’s no indication it’s running) for about 30 minutes on a first pass of a huge runtime.
When it stops producing its occasional “RSR could not be converted… Sorry!” messages, and lets you slide the scroll bar, then it has finished its run.
With Poser 11’s new Comic Book Preview mode, a lot of older content with fuzzy/muddy textures can become useful once again — for a cleaner cel-shaded/comic-book style. The underlying model geometries are still fine, so you’d just swop out the older textures for a flat toon style material.