I enjoyed the "carnie girls" collection of vintage paperback covers from the Good Girl Art website. Shown here are covers to two (sadly out-of-print) carnival-themed books I highly recommend: Madball, by Fredric Brown, and Nightmare Alley, by William Lindsay Gresham. (Update: Nightmare Alley is available in the anthology Crime Novels: American Noir of the 1930s and 40s.)
Good Girl Art, usually shortened to GGA, is the term that describes certain types of Vintage Art, and specifically Paperback Cover Art. Richard Lupoff in his The Great American Paperback defines it as "A cover illustration depicting an attractive young woman, usually in skimpy or form-fitting clothing, and designed for (mild erotic interest). The term does not apply to the morality of the 'good girl', who is often a gun moll, tough cookie, or wicked temptress." The GGA designation seems to have originated with comic books and is usually applied to attractive sexy young women who are either in peril or are perpetrating the peril like my favorite gun moll on the right. So it is often politically incorrect but can also be empowering when at the right end of a gun.