Manufacturing quality matters, too. Cheap stainless steel (e.g. basically anything from a Lowes or Home Depot, or elsewhere standards aren't rigorously enforced

Manufacturing quality matters, too. Cheap stainless steel (e.g. basically anything from a Lowes or Home Depot, or elsewhere standards aren't rigorously enforced, like so much exterior cladding, trim, and fasteners on modern construction) will often rust almost immediately in spots as the alloying isn't sufficiently homogenous or pure. See https://en.wikipedia.org/wiki/Nickel_pig_iron https://en.wikipedia.org/wiki/Nickel_pig_iron