Yeah and other CAGs may resort to buying used controllers and if they come across your broken one because you thought to trade it in as 'working fine', they'd be pretty pissed off. I'm sure you would too if you were in the same boat.
Dude you are preaching to the choir, what you are doing is like spitting on a wildfire. There is so much of this that goes on that you don't even see posted here. The last thread alone had numerous people asking the exact same thing.
The moral of the story is don't buy used game hardware at GS. GS's own model of testing is flawed. the 360 is the most broken console in the history of video games and they STILL playtest them for less than 5 minutes before saying they are good. If they don't care they are buying broken crap why should you?