I'm not sure how much I would trust these secondhand cards either. I suspect quite a lot of newbs jumped into their first PC build as a 6-GPU mining monster hoping to make their fortunes, and bricked the cards with a bad BIOS flash, overclocking or hotswapping.

It seems a bit daft to lay out that much investment and waver at the first price drop. Most domestic mining rigs aren't going to see any ROI for six months. The more canny miners will be glad the noobs bailed which will slow the difficulty increment and increase any pool share.