I like the idea of an alternate icon for the found icons, or it could be a new image overlay that could be unchecked. I don't know how flexible google earth is for personalized content (ie. checking gc.com account-specific info), so it may not be feasible, but yes, it'd be nice.
While you're at it, it'd be great to further customize the list of caches displayed - ie. by type (multi, traditional), size (micro, small, regular), date created (within past year, month, week), etc. Yeah, I may be dreaming.
And to take it even further, can you imagine being able to select various caches (either by individually clicking on them, or by dragging a box around an area) and saving them to a .loc or, even better, a .gpx format. This would eliminate the need for pocket queries, especially if one could schedule these selections to auto-generate on a user-specified schedule.
It's fun to imagine, and maybe 6-12-18 months, some of these will be possible.