I read that tasting butters, e.g. eaten with bread, or finishing in dishes like risotto, need to be better quality but for pastry and cooking, cheap butter can be okay since the delicate subtle flavors gets cooked off and muted. I wonder how much of that is true though, maybe there's some threshold tradeoff of how much the taste of a final dish would improve.
For something like an omelet (which I make every day for breakfast), it's bland enough that you'll be able to tell because the flavor of the butter used is a substantial part of the end result. I daresay there are things you could cook that are spicy enough that you'd lose any distinctions, but I'm not used to 'monter au beurre' with any of those. My loss, perhaps?
