I don't mind sales where items aren't marked. I always ask how they are selling the fabric -- by the yard, by the piece, or what. The answer to that question gives me an idea of what they have in mind and how negotiable they are. They often tell the whole story on the fabric and that itself reveals a lot.
In addition, frequently sales where prices are not marked often are the sales where if you bring a pile up to the seller, you will get a good deal.