If you have one item in stock and someone buys it, the listing is not supposed to appear to buyers at all. If you use the "out of stock" option from eBay, the listing will go to 0 stock and should not appear in the store or in any search results (this is what causes the postage error 99% of the time, by the way, for some reason eBay suddenly can't pull the postage details from an active listing with 0 stock).
If you don't use the out of stock option, the listing simply ends, so again won't appear in the store or in search results.
I have noticed that when I view my own store, I can often see my out of stock listings, but I don't see them when I'm logged into a different account.
I've also noticed some of the bigger retails stores still have OOS items showing in their store, but they have "Out of Stock" banners across the gallery image, and this option isn't available to general store holders (as far as I know, since I've only ever seen stores like Target and Good Guys have it).
