Judy, during times of wine glut, house label wines can be a bargain. In the early 80's, we used to pick up some super cheap bottles at Von's or TJs that were worth 4 to 7 times the price. However, despite forecasts year after year for the last 5, the wine lake has not yet materialized in Calif.
House label wines can come from wineries that go bankrupt or miss a debt payment and the bank sells off wine in bulk or unlabeled bottles to raise cash. In good times like today, they tend to be lots that don't fit into a large winery's product line or have too distinct a flavor to blend into the house style. That doesn't mean they're necessarily bad.
Some of my best luck in finding bargains has been to examine the packaging. A distressed winery will use the same packaging, sans label, it has on hand rather than trying to find small quantities of something else. Look for heavy glass bottles with a punt (the indentation on the bottom), long metallic capsules rather than flimsy plastic, and long corks. These can add more than a buck to the cost of goods and are indications that this wine was made by an upmarket producer and originally intended for a premium market. Sometimes the corks are imprinted with the winery's name. Also look at the label legend, the line of fine print that says, "Vinted (or produced) and bottled by ______, address" to get a clue of who made the wine.
When you find something that's priced to move, best to pull the cork in the parking lot, try it and see if you want to buy more. Otherwise it might be gone by the time you get back.