Depends. Are we taking refurbished, or returned sales?
Refurbished is going to have to be hella cheap to consider it for a highly redundant storage of unimportant things maybe raid 10 backup storage it something.
Returned sales are mostly still as good a new and returned for various unrelated reasons. As long as I get full warranty and right to return as if it was brand new, i don't mind.
I run used disks with tens of thousands of power on hours. Yes the risk of each disk dying is higher but only marginally and the cost is dramatically lower. To avoid data loss when they die, I have functioning backups. This system is working really well for me.