Not sure I understand the mining reference. Never did really. Mining cards are barely used, there's no graphical output, almost all are run pcie x1, almost all are lowered voltages, running minimal to remain stable at what they are doing. If anything, I can see mining cards suffer less actual abuse than most ppl who have this absolute need to apply rediculous OC to an OC card. And yes, I ran my 660ti and 970 at 124/128% OC respectively, so I understand the abuse they saw.
The only real objection I see to mining cards is their fans run 24/7/365. Ok, that's an easy enough fix that's relatively cheap.
Like Darkbreeze and others, there's 3 things I personally absolutely will not buy used. Gpus, psus and storage. Anything else is fair game. But thats me.