Most of the China sellers work as follows:
They set up an auction for a CD or DVD. You buy it. They go down the street and buy it at a store for $2 or less, and mail it to you, pocketing the rest as profit. Yeah, these $2 CDs and DVDs are usually high quality pirates, but still pirates. I spoke to a gentleman at length about where he got a particular DVD and that was pretty much his answer. So you usually _aren't_ dealing with the pirates, themselves. Just some student buying discs from a local store.
Though me never did bother to send my money back. Oh well.
I've also unintentionally bought some very high-quality pirates from the Russian Federation on eBay. I did notice the tonal balance on those CDs (about 12 for $36) were tipped up in the treble. Pitty as those CDs were out of print, but I was able to compare it against the one that I did have.
I've learned to avoid these auctions.