There's a few items that I keep towards the top of my invo that are "just in case" things, like those basic bras/shorts/panties/shirts that are as old as the website itself. I've actually used them a few times in newer avis to like "fill in the gaps" of some outfits, but I usually don't touch them. But I do have two weird ones I hold onto even though I
never ever use them.
I hold on to these 2 -


- because they're two of 3 (maybe 4?) items that you can use to make your avi invisible, like for scenics. There's specific poses in each them that, when all used together, erase your avis body so its just the background and/or any foreground items.
It's one of the older methods for disappearing your avi, and I remember never being able to get my hands on the last item(s) I needed for it. Plus, I don't even want to do scenics anymore

so idk why I hold onto them. Like you said, its a "just in case" thing I suppose.
EDIT:
Here's a quick using both of them to make a spooky edgy avi, lol (in spoiler because its a tiny bit gory, so just incase anyone doesn't like that...)