Haven't seen them until now :D
Don't think they will have a large impact.
Most people don't even put the "closed" prefix infront of their trade when they are done so I wonder if they will use these.

Edit: I've added them to my threads now and they look nice. Although I don't get the difference between sell and trade since in both cases you get rid of the item you don't want. I rarely see someone use it on the feedback section. In my opinion the prefixed Buy, Sell, Closed should be enough
 
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.
 
One other thing I'm noticing is that the text color for the "Buy" tag should probably be black. The current color pattern makes it look like the like it's an inactive button or something. I think black text would be more uniform among all the tags.
 
We don't need a tag saying shop. If you sell something just add the prefix sell. All a shop does is selling items.