dirty blues means: The term blues music that is often extremely lo-fi and has explicit or suggestive lyrics, such as in the 1930s. All of these are very old blues songs that extolled drugs and the enjoyment of sex. These songs are often considered early, illegal, underground music. They contain explicit lyrics that were written by many black artists. Some of them even lean toward lesbianism like Lucille Bogan. (in Community Dictionary, added by Charlie Goodwin)