Is "straight bourbon" a mark of higher quality than plain bourbon?

"Straight" is a specific regulatory bar under 27 CFR § 5.143: the whiskey has to be aged at least 2 years in new charred oak, and it can't contain any added coloring, flavoring, or blending spirits. If it's aged less than 4 years, the label also has to disclose the age. Every straight bourbon meets that floor.

But meeting a legal floor isn't the same as tasting better. Plenty of straight bourbons are unremarkable, and non-straight bourbon (which is still held to the core bourbon standard; just without the extra aging/no-additive rules) isn't automatically worse. "Straight" tells you about how a bourbon was made and what's in it, not about how it tastes.