If I have a question about whether or not a toy/book/game/movie is appropriate, I contact the parents and ask them. If I can't get in touch with them before I need to purchase the item, I don't buy it and buy something I know is appropriate.
Generally, I trust parents to parent their children so if I do indeed buy something that they don't approve of, I am pretty sure the parents can take care of disposing it, hiding it, putting it away.