I've seen several people suggest that droplifting is a good way for writers to promote their self-published books: but I think it's a terrible idea.
Droplifting is shoplifting in reverse and involves surreptitiously leaving copies of books on bookshop shelves in the hope that someone will buy them. The obvious problem is that while the books will physically be in the bookshop, they won't have a virtual presence in the bookshop's computer system and so if they ever do reach the checkout, the cashier will be unable to sell them. If there's a manager on hand to authorise the deal the shop will probably just give the books away: if there's no manager available the books will be put to one side and will probably end up in the recycling bin or dumped with the sale items. But as booksellers tend to be aware of their own stock, chances are that one of the shop workers will spot the droplifted books on the shelves, recognise that they shouldn't be there, and dispose of them within hours of their deposit.
How ever this is worked, the writer loses money. How does the writer benefit? And what on earth do they think they will achieve by doing this?
ETA: Marian Perera, over at Flights of Fantasy, has written a much better piece than mine about droplifting, which you can read here. Thank you for the link, Marian!