Yes, that's exactly what I mean. Because one movie has a song that during one scene (a boxing scene no less) is more or less interchangeable with a similar song, seeing as the scene and song have no connection deeper than "well, it sounds pretty cool right here", that all music in all movies ever are interchangeable with songs of similar tone and tempo.
Yes, the score to The Good, the Bad, & the Ugly could be exchanged for a different score (although probably only other Ennio Morricone music), but even then something is lost. There is a deeper connection to Morricone's score and Leone's imagery than just "hey, they go together". Whereas, in Snatch, it would not be lost, because there is no deep connection between music and imagery in that particular scene.
My point was that Mann may have not used the best song for that scene, but it doesn't exactly clash with the imagery either. Everybody always wants their favorite music stuck somewhere into movies they like, but sometimes it's just impossible. Maybe the song Mann thought best fit (from what I've heard of the guy, he isn't one to just put 'hot" music into his music for the sake of selling more CDs or tickets or whatever) isn't what you or I, or even most people think fits best.