With one exception, I've always been pleased with my purchases. Years ago, there was somebody selling who never filled orders, and there were several of them. A moderator got involved, there was an explanation of a sick family member,then car troubles, and so on. She'd run the same scam on another forum. To my knowledge, nobody got their money back and the person was banned. Those types of experiences are few and far between, I'm sure.
The items I've purchased were specific brand fabrics, not labeled simply "LQS quality." There are scads of threads about big box fabrics being the same as LQS fabrics; if a seller is of that mind (and everyone is entitled to their opinion), then they could be selling just about anything.
If the price is right and that's okay for you, give it a whirl. Or ask before buying if, should you not be pleased, if they would allow you to return it. My guess is that most people would be okay with that, but you'd lose on shipping costs both ways, as well as possibly having to wait on having money refunded.
Personally, I'd rather just buy those that are brands I am familiar with.