Depends on what it is. But it sounds like many are lumping together generics with store brands. I specifically remember when one local supermarket started selling a group of literal generics in the early 80s. The all came from a single distributor that used plain yellow labels.
With medications - absolutely no problem. Ibuprofen is ibuprofen. There's almost nothing gained from using name-brand medications when there's a generic equivalent. If I need a decongestant, I'll buy the cheapest store brand or nonbrand. At Costco they've got some that actually says Perrigo on it, which is one of the largest makers of generic meds in the country. If I buy them as store brands, the blister packs typically state who the manufacturer is, like LNK or Perrigo.
With prepared foods - that's a very different thing since flavor profiles can be very distinct. But store branded food can be pretty good sometimes, like what I can find at Trader Joe's. There are also certain things that make no or little difference like cooking oil, but somehow people still pay a price premium for something with a neutral flavor that isn't terribly different. There are also certain foods that are essentially commodities like dried beans or frozen vegetables. I've found frozen vegetables from a no-name brand that seem to be fine compared to Birdseye or Green Giant branded. They all come from growers cooperatives anyways.