MOST FOLKS KNOW THAT buying store-brand products (also known as private-label brands) is a great way to cut costs.

But despite the lower prices, not all generics will save you money. Here are five to forgo in favor of brand names:

1. Coupon-Laden Items

There's no need to buy Brand X peanut butter when you're really craving Skippy Super Chunk. Contrary to what you might believe, store brands aren't alwaysClick here The key is to maximize store sales and manufacturers' coupons, says Teri Gault, founder of The Grocery Game.

2. Cleaning Supplies

"If you're looking for something for basic cleaning, you're probably OK with a generic or store brand," says Carolyn Forte, homecare director for the Good Housekeeping Institute. But if you have a really tough mess to clean up say, red wine stains on your carpet or pervasive mildew in the shower splurge for the brand-name product.

To keep prices low, store brands and generics contain more water and less of the active ingredients that give the product its punch. That means you'll use much more of the product. In Institute tests of dishwashing soap, a squirt of most store brand dishwashing soaps cleaned only five or six dishes before the suds broke down. The same amount of name brands such as Dawn, however, cleaned nearly 20 dishes.

3. Paper Goods

Here, a lower price usually means fewer fibers or even single ply instead of double, both of which translate into poor absorbency, says Phil Lempert, a food marketing expert and author known as the Supermarket Guru. "It might cost 20% less, but you're going to use 50% more," he says.

In an August 2005 report, Consumer Reports found that out of the 10 store-brand paper towels it tested, five including "poor"-rated Kroger Everyday (70 cents) and Stop & Shop Pure Power ($1) were very flimsy and held little liquid. And tissues? "You might need more than one of some tissues to do the work of a single Puff," the report said.

4. Pet Food

Whether you're buying Fido bags of Ol' Roy or Pro Plan Select, the food inside is nutritionally adequate, says Dr. Sean Delaney, vice president of the American Academy of Veterinary Nutrition. Per federal regulations, pet food must carry a statement of nutritional adequacy from the Association of American Feed Control Officials. Still, actual ingredient composition can vary from brand to brand.

Low-quality brands may scrimp on items that remain important to you and to Fido if not the U.S. government. When you splurge on a better brand, says Delaney, you're generally getting increased fat content for a glossier coat and a more consistent product bag-to-bag. You'll also likely see higher-quality ingredients (say, chicken instead of chicken byproducts, which includes heads and feet).

5. Diapers

Baby diapers are a major expense: You'll go through about 8,000 diapers per child, according to Consumer Reports. While there's no significant difference in absorbency when comparing generics to brand names, there can be radical differences in fit, says Gault. And, as any parent will tell you, a leaky diaper makes for one cranky baby and an even crankier Mom and Dad.