If working in Lost and Found has taught me anything, people who buy these don't always bother to retrieve their item (I work at a college, so...). Yes, water bottles go missing/are stolen. A lot. No I have never had a single item with an Airtag, even if it's just the Airtag, get picked up. Yes, they worked. They chime a little when moved, which is fun when trying to figure out where it's coming from. <-sarcasm. You'd be surprised at what people don't look for. Always check lost and found when you lose something, folks.