I don't think it's fair to label every single person selling discounted gift cards as blackhat. Many people receive these at gifts or through discounts (for their birthday, christmas, from their work, etc.) and are willing to sell at a discount because they don't plan on using it. I have personally sold gift cards at a discount because I value the freedom of cash over the purchasing power of the gift card.
I never said everyone is but you have to think about what you said.
People who receive gift codes as a gift and want to sell it...would only sell one. Not open a shop.