"Good Girl" art is a category that transcends normal comic book genres. Humor, adventure, sci-fi and more have all featured "Good Girl" art. "Good Girl" art is usually drawn in the pin up tradition. The scene might be risque for the time of publication. Prominent breasts (known as 'headlights') were the rule. "Good Girls" were usually athletic, smart women who might fall into precarious positions. So what about "Bad Girls", you ask? Criminal bad girls are a much rarer breed, but they do appear.
Romance comics are fairly self-explanatory. They are comics for girls and feature stories of love and romance, often with surprisingly adult themes and situations.