I suggest comparing. By your normal 'name brand' as well as 2 or 3 off brands. If you can't tell a difference, or the difference is more than offset by the price gap, then go generic.
I'm a pretty frugal person and I generally look for the best bang for the buck, usually price per ounce on food goods. WalMart is pretty good about listing this info on their price tags.
Take American cheese for example. For processed cheese food, I don't know why it is so expensive. Kraft is pretty outrageous, nearly double the cost of the cheapest alternative. My wife insisted on buying Kraft because that was what she grew up with and all the other brands were 'nasty'. One day I bought one of each, 5 or 6 packages total. I staged a blind taste test with the label under the plate and a single slice of cheese on it. We tried each one and discussed the flavor, color, texture, etc. True, the worst one was 'really nasty' (it wasn't the cheapest, though!), not much better than yellow wax. But after she arranged them in order of her likes, she was suprised to lift up the plate & find that her favorite wasn't Kraft, in fact, Kraft had fallen to 3...
So, now, she doesn't make a big deal about getting Kraft. We've done similar comparisons on different things, some the generic varieties are really poor quality and we stick with the brand names; canned vegetables, for example. We tried a few generics and found rougher textures, stems, leaves, etc. in things that shouldn't have them, like green beans <shudder>. For the items that we can't tell a difference, we go for the extra 10-30% savings on the cheap variety. We've even found some generics that we like better than name brands.
My advice: Before you rule out generics, give them a try. You might learn something. And if you add up the savings over your lifetime your looking at a pretty hefty investment.