As a savvy consumer, there are many instances when I am food shopping and am faced with a dilemma:
Name brand or store brand?
Sometimes the difference in price is negligible. Other times, it is quite significant. But of course, the cheaper version is almost always of an inferior quality, so it may not be much of a "discount" if you constantly lament how bad the food or drink tastes.
The following is a guide of when it is okay, and not okay, to purchase the generic. For your reference, Kroger is my store of choice.
Canned Fruit
Store brand canned fruit can be significantly cheaper - if say a can of Dole mandarin oranges costs $1.50, the store brand will likely cost a dollar. For the discount, you get generally the same weight and quality, although the actual pieces of fruit are a big smaller. Still, its not like you're getting less weight in fruit, so I have no problems with buying store brand canned fruit.
Marinades
Usually there is a brand name marinade on sale such that it is as cheap, or almost as cheap, as the store brand. That being said, most of the marinades seem the same to me, so I just go with the cheapest. You should feel entirely free and comfortable when purchasing the store brand.
Soda
This is one of the biggest problems for generics. No matter what store brand knock off you get ("Twist-Up" for 7-Up, for instance), it will taste absolutely nothing like what it is supposed to. Since almost all of us are conditioned to like the particular taste of Pepsi, Coke, Sprite, or Dr. Pepper, the store brands fail miserably in attempting to offer a cheaper alternative.
Tinfoil
Okay this is not a food or drink item. But I bought the store brand tin foil that was on sale, and it was a debacle. It was too thin and too wide at the same time. However, I then purchased the Harris Teeter brand tin foil, and it has served me well. So the lesson may be that tinfoil depends on what store you buy it from. A high end store like Teeter will have quality tinfoil, while a Kroger will not.
Hamburger Helper
Hamburger Helper boxes can be as expensive at $2.50 when they are not on sale. On the other hand, "Hamburger Magic" from Kroger usually costs $1.00. I eat the "Cheeseburger Macaroni" version all the time, and I truthfully cannot tell the difference between the two. However, if you catch the right sale, Hamburger Helper will be on sale for a dollar a box, and you can always stock up then, if you wish.
Boxes of Rice
On the other hand, at all costs avoid the store brand boxes of rice. It is absolutely incredible how terrible the generic box of rice tastes in comparison to Uncle Ben's or Rice-a-Roni. On sale, Rice-a-Roni or Uncle Bens should run you about a dollar a box, which is still more expensive than the store brand, but is well worth it.
Chicken Pot Pies
I do not have any first hand knowledge of this, but I know Wilkins said that you definitely get what you pay for, and that he would never buy the generic version again.
Macaroni and Cheese (the kind you add milk and butter to, not Velveeta style)
Way back during freshman year at Duke, I would bring numerous boxes of the Acme brand of macaroni and cheese. On the cheese package it said something like, "KF094 Cheese Flavor Sauce," which me and Ben got a big kick out of it. We would make up boxes of the stuff and it would glow bright orange. It tasted phenomenal, to the point of where I actually preferred it over Kraft or other name brands. If you can deal with potentially exposing yourself to chemicals not fit for human consumption (but taste darn good), I wholeheartedly recommend store brand mac and cheese.
Orange Juice
I usually go with Tropicana or Minute Maid - they just taste a lot better than the store brand. Also, they have special things added, like calcium, immunity defense nanites, or Vitamin E. Don't short yourself on something as important as orange juice, unless you're buying it for mimosas or screwdrivers.
Hopefully this guide will help you the next time you go food shopping.