Instrumental music is so subtle.
I recently had a back-and-forth regarding acceptable music content with a friend. Music, like all things in life, must fall into one of two categories: of G-d, or of The Adversary. How we determine in which camp the melodious tent is pitched is based on content and the presuppositions of the artist.
That's easy enough for the latest Ke$ha song, and even for more te poetic John Mayer song, but what of instrumental music?
I guess you just have to _feel_ it :)