I have found some amazing and wonderful goodies there. I found 2 large bags of wool yarn and decided to sell some of it in my Etsy shop. They sold quick but then one buyer had to leave a crap feedback. Now tell me how hard is to contact the person you purchased something from and let them know that you aren't happy. Instead they just leave a neutral feedback. I have no knowledge of previous owners or where the things I purchase may have been. I just get excited at an awesome purchase.
About a month ago I found a vintage sewing basket at the thrift store with probally 150 spools of vintage thread. Now I really don't need that much thread so I list some and now I have to hope for the best.
So the way I see it is if your a picky person stay away from vintage items because you never know where it has been or who may have had it last.