Re: buying generic:
In my experience, quality varies tremendously by generic brand. For example, America’s Choice (the now-defunct A&P brand) products were decent but not quite as good as brand-name ones; Kroger brand stuff (especially the dairy products) are excellent; while Stop & Shop brand stuff ranges from sub-par to abysmal.
Of course, some products are such that it’s difficult to impossible for them to be meaningfully low-quality, and any inferiority in the off-brand stuff will be along dimensions that are orthogonal to “quality” per se. For instance, if you buy generic-brand granulated sugar, you will often find that it’s full of stuck-together clumps, rather than being uniformly separate grains (as is almost guaranteed when buying brand-name). But this obviously does nothing to affect its edibility—sugar is sugar!