I think an additional prefix should be added for "Shop", for users who are selling a large list of items. "Sell" prefix could be used for people who have a small amount of items, like some Genuine set or something, where it's a one-time use thread, whereas "Shop" could be used for multi-use threads for users who have a large stash of goods that they're selling.
But I think the new tags are definitely nice, though. Helps to quickly find a thread that I may be interested in, depending on what kind of trade I'm looking to do that particular moment.