My DS Phat, bought in 2005, broke last year (hinge split). Well not really, it still works, but it annoys me because I'm such a perfectionist. Besides, it was all my dogs' fault! See, I had it plugged into the wall to charge, and set it up on the table. My dogs then decided "Hey! Let's roughhouse near that silly cord!"
...You can probably guess what happened next. I was extremely lucky, because SoulSilver escaped the incident unscathed.
Before that, my DS Phat had no scratches on it, despite five years of playing. I could have posted it on eBay as "brand new" and the receiver wouldn't have noticed.
My frontlit GBA SP has taken massive punishment in the eight years I've had it, and there are scratches to prove it, but it still works like a charm. The screen's totally intact, the hardware's still free of damage, but the chassis is so banged up you'd think it could never work again. Alas, I still use it for my addiction to Metroid: Zero Mission.
I also have a regular GBA, a GBA Micro, a GBC, and a GB Model 01. All of them still work perfectly (except the Micro, which has a faulty L Button) and I could market them as "brand new" (the GB has my grandpa's name written on it, but that's fixable).
A few months ago, my cousin took a hammer to my GameCube and threw it against a brick wall. The other day, I beat Metroid: Zero Mission with it (using the GB Player). No scratches, and it works just fine.
In terms of games, I've witnessed the corruption of numerous saves, but the only one which I'm directly responsible for is my old Sapphire version, which I messed up with an AR.
My old copy of Zero Mission was constantly corrupted, periodically wiping the game completely, because of my stepbrother.
My old Silver version's save battery bit the dust back in 2007 (shortly after I rediscovered it after it went missing for about four years), but that happens to everyone. My Crystal's still intact, though.
Aside from those, all of my games are squeaky clean... I take enormous care of my electronics.