Actually, I use Great Value products on a regular basis, but with two caveats: 1) I NEVER use generic dairy products (which is almost all of what you said you have tried) and 2) I never expect name-brand quality or performance from generic products.
You seem to have gone into these purchases without the correct mindset. While generic products can sometimes be a good way to save money, you never consider them an equal replacement for the real thing - that way you aren't disappointed when they don't perform well, but you are pleasantly surprised when they do.
With that said, however, I have used many Great Value products in the past and continue to do so now that I have been happy with including, but not limited to, cereal, kool-aid, uncooked pasta noodles, etc. I have also used Great Value products that I have been very unhappy with including, but not limited to, paper towels, paper plates, some canned vegetables, etc.
It is definitely a trial-and-error process with generic products and you have to be willing to put the time and effort into finding which ones will work for you and which ones won't. Otherwise, just purchase name-brand.
I hope your experiences get better!