Used to work in CeX; you wouldnt believe the state of some of the controllers people have attempted to sell in. Moreover, when you attempt to point out the glaringly obvious faults with said controller/hardware, they pretend that they cant see it :tsk:
If the sales dude brings out a manky looking controller, just tell him/her to (please) go get another one to sell to you.
alternatively, if you're lucky, there are people out there who somehow manage to acquire brand new hardware which they then sell in bulk to CeX. So essentially, you might be able to get your hands on a brand new controller @ CeX prices. Depends on CeX store location though.