I'd say the other way around. The store brand version has nearly always been fine, in my experience. I'd instead use the store brand and make a list of cases where the store brand isn't okay. At least in my experience, it's pretty limited. What I can recall having bad experiences with, off-the-cuff:

• Soup. I have had some pretty disappointing store brand canned soups.

• Things with motors, like small kitchen appliances, blenders and the like. I've had a bunch of generic ones of those fail before.

• Sodas. These aren't exactly the same. Some people particularly prefer the taste of one root beer or whatever, and it might be that they prefer a name brand. That being said, there are also people who prefer store brands, so...shrugs

There are also a few cases where I've run into a particular brand that doesn't have a store clone, and where I really like the name-brand product.

• Pretzels. I particularly like Dot's. I haven't seen a store brand clone of Dot's.

• Sardines. Bit of a niche, but I once went on some website with some guy that was absolutely rabid about sardines, reviewed them, wrote huge amounts about them. My dad always liked eating canned sardines on crackers. Tried a couple different brands, and yeah, there is a difference, but the big one is that stores in the US don't normally have heavily-smoked sardines (well, okay, sprats) in oil. I started eating Latvian "Riga Gold" sprats in oil, and they're just amazing. I don't like a lot of foods I've tried from Eastern Europe, but man, they hit it out of the ballpark on that. I don't think that we have a US-based comparable manufacturer.

• Red Windsor cheese. It's not all that fancy, just cheddar with some port wine marbled in, but I really like the taste. Same thing on this -- I don't think that there are any companies in the US that make the stuff, so it's name brand or nothing.

If someone did clone any of the last three, though, I'd give 'em a try.