On Tue, Dec 3, 2013 at 12:41 PM, Gavin Andresen <gavinandresen@gmail.com> wrote:

If users want to pay with a huge transaction then it seems to me the user should cover that cost. Allowing users to pay merchants with 100K transactions full of dust and expecting them to eat the cost seems like a great way to enable bleed-the-merchant-dry attacks.

A merchant can always refuse the payment and refund it if that's a practical problem. I doubt it would be though. If a user is trying to buy something from the merchant, they will want it to work, and it'll be up to the developers of the wallet they're using to ensure it never does anything obnoxious or unacceptable that would result in people hating to receive money from that app.