This is common with Best Buy. Over the years I got 2 ipads, 1 ipod, and 1 laptop which hadn't been properly wiped. Furthermore they were sold "as new" with an as new price.
What is the suggested course of action if you return a machine/device to one of these stores? You could do the factory restore yourself but how do you know it overwrites the entire drive? Seems like the only solution is to wipe all disks from a Linux thumb drive before taking it back. Probably best if you just tell them it won't boot and leave it at that. This way you force them to restore the factory image from scratch if they want to resell it. Wipe with zeros or use random data those are your only options...
