I have had my original DS since they first came out and I don't protect or carry it in a case...It works perfectly fine, touch screen is still the same and everything. I throw it on the floor every night because I dont have a nightstand or any kind of dresser near my bed, so I just toss it on the floor when Im done playing before bed....

Although I have noticed that on the top screen, every once and a while one little pixel will always be a light bluish, i use to think it was part of the games. But if you turn it off and turn it back on it usually goes away. Maybe I should stop throwing it....