Hold on a second. First of all, it is "blues" not "blues music." Secondly, there is no room for discussion of scales - diatonic or otherwise - when talking about blues. And Dorian? 7ths just happen in the blues. It is part of the genre. (hmmm, have I violated my own rule in using a word as un-bluesy as genre?) Some time one speaks in terms of I, IV, V or maybe 12-bar. But genuine music terminology - I should say not!

Of course I am kidding, but the blues is all about feel, much more so than about musical analysis. To much dissecting and you wind up with the whites.

dw