Two major problems involving "unsanitized" folksong existed in the thirties and forties (and, indeed, to a great extent, up through the sixties): First, nobody would publish "dirty" songs, particularly in a scholarly-type publication. This was a particular sore point with Vance Randolph, who really tried (unsuccessfully) to have bawdy material included in his fine Ozark Folk Song collection. The second point is that many of the great collectors of that era were women, and it was very difficult for a woman, in those Victorian-influenced days, to get anyone to sing a "dirty" song to her. Upon reading what I just wrote,I guess I should add a third problem: Blue material just wasn't considered worthy of study until recently (unless Child included it). Ed Cray's "The Erotic Muse", Logsdon's "Whorehouse Bells Were Ringing", and Randolph's book whose name escapes me at the moment,are all recent, and are probably the first books that dealt with this material as folklore to be studied, although a few collections of off-color songs had been published previously.