I've heard the same thing. My mother wasn't overly concerned about us getting germs. I remember her telling a story about letting me sit and play in a mud puddle when I was a toddler and the lady next door coming out and telling her she shouldn't do that because of germs. My mother said "A few germs never hurt anybody. How else will she build up any immunity?" I think she was right.

And, yes, someone has to be the original owner. I donate a lot of clothes just because I'm tired of them or they are out of style/don't fit/just don't like anymore. I always hope that someone else buys them who will appreciate them.

I think I would bet that a freshly washed garment purchased at a yard sale where the garage is immaculate would be as "clean" or "cleaner" than almost any garment found in a department store.