The famous 'wrong' scale that's righter than right — but only in the right room. It sings when the tonic wears a dominant 7: over a 12-bar (1⁷ 4⁷ 5⁷), a riff vamp, or anything where the band's thirds are thick, distorted, or ambiguous. The b3 isn't an error there; it's a blue note leaning on the major 3rd — bend it up a quarter tone and you're speaking the dialect. The b7 matches the tonic's own b7. This is why the blues scale works over a 'major' progression: blues tonality isn't major or minor, it's both at once, and this scale is its voice.