If your still not happy with it after the above tips, pm me before you sell it back to him, what all is there and how much you paid the guy. That way you get your money back, and I get some gameboy stuff 
It's funny you say that. Almost all of the games in the set were doubles anyway. I'm going to try can clean everything and use the advice from this topic to get everything back to normal. But no matter what, I will still have some doubles for sale.
The games that I will be selling are the following:
Game Boy
Donkey Kong
The Legend of Zelda: Link's Awakening
Mortal Kombat
Tetris
Game Boy Advance
Super Mario Advance (Super Mario Bros. 2)
Super Mario Advance 2 (Super Mario World)
Super Mario Advance 3 (Super Mario World 2 Yoshi's Island)
Obviously, the game may have some smoke damage, but hopefully I can eliminate some of that.