I agree that once fired brass should be just that, factory ammunition that has been fired one time. If it is not known to be that then advertising it as once fired is disingenuous at best.
Having said that I now either buy factory ammunition or new brass if it is important to me to know precisely what it is. I have some rifles that I use in the field and it's unlikely I'll recover the brass so I'll use range brass if I'm not particularly concerned about the best accuracy possible.