I am reporting him because he took advantage of a steam glitch. He pretended to sell me a Dirt 3 Steam Gift but it turned out that I got a useless Gift instead. After I took note of this I contacted him on steam again. He says it is not his fault and he won't trade it back. Also, he just offered me 2x tf2 keys with lousy excuses instead of a full refund of 5x tf2 keys. This behaviour shows very poor trade ethics and bad moral.
I also fell a victim of this glitch, I was sure this is Dirt 3 when I bought it and when I sold it. However, I offered Unknown package 44320, which is Dirt 3 according to SteamDB, as you can see in the following link
This trader agreed to buy Unknown package 44320, hoping that steamdb is correct.
Several days after he says that the gift changed its name and turned out to be a whole different game. I feel sorry for him, as my words about steamdb turned to be misguiding, but he's an experienced gift reseller and knows the expected risks and profits. I offered a partial refund as a good will gesture (he refused, insisting on full refund only), but I don't think that Steam glitches are my responsibility.
That is why I think that I did more than enough to fulfil my obligations on this deal