Find a trash can
Occasionally, when I’m wandering the store doing my shopping, I will see items sitting on shelves where they don’t belong. Usually, this is because another shopper has changed their mind about a purchase when they’ve seen something better, or perhaps they’ve decided they don’t really need that item.
This is even worse, though, because you’re not changing your mind about something that even belongs in the store. You’re using the shelves as your own personal trash can and expecting the shop assistants to clean up after you. That’s not really their job, and you really need to be more responsible for your trash.