As a seller, I tend to start my sale at $5/yd because I originally paid $10/yd for my fabric. I think a 50% discount is fair to begin. I then lower the prices for the pieces that are slower to move. This helps me to clean off the shelf and the buyer to get quality fabric at a discounted price. Another thing is that a majority of my sales usually end up in a trade. I think that is what makes it fun for me.
As a buyer, I send a pm to ask what the manufacturer of the fabric is if I am unsure. Ultimately, it is the buyer's responsibility to confirm that the fabric is the quality they prefer.
Just my opinion.