So what is a shiner?
Why do shiners exist?
For a winery, they often end up with some extra juice and they don’t necessarily want all that extra juice to effect the price people are willing to pay for their wine. It’s a hell of a lot easier to make a lot of wine go away if it’s in shiners, rather than if it’s in a labeled bottle. It’s also easier to sell a shiner than it is a barrel of wine, after all not every retail client has an easy way to get that wine into bottle.
Plenty of restaurants and stores do wines under their own label, which often are originally purchased as shiners.