Here's one way I do this. I keep odd sound files segregated out of my normal views. In my case, this includes test clips like Pink Noise, Sine waves, etc, as well as Sound Effects (like rain and that kind of thing).
To do this, my main OUTER view Audio, has two rules:
[Media Sub Type] is not Test Clip
[Genre] is not Sound Effect
Because Audio is the Parent view of ALL of my audio views, every view inside of Audio automatically excludes Test Clips and Sound Effects.
Then, outside of Audio, I have another main Outer view called "Other Audio" (not very descriptive I know). Other Audio has two rules:
[Media Sub Type] is Test Clip
OR
[Genre] is any Sound Effects
So Other Audio *only* shows me the "odd" files that I exclude from my main Audio.
You could do something similar. It's just a matter of figuring out what you might want to call your other category. Then deciding whether it's smartest to categorize these "not very often listened to" files with a Genre tag, or a Keywords tag, or something else. If you predict that you might have more files like this in the future, then a Keywords tag might be best. Something descriptive like "Exclude from Main", or "Not Popular", or "I don't know why I have these" .
Then just build your views based upon the Keywords tag and you're all set.
Brian.