no one can say that they have not been used for a long time for intensive mining, i.e. overclocked, and that therefore they are useless, at the end of their life.
Video cards are not potatoes.
People overreact with this whole mining thing, a GPU that has been mining in a correct environment with cooling and no power fluctuations will be just fine, everyone forgets it's just circuits, just as you have cpus lasting decades you can have videocards that have run 24/7 still going for years.