From Salon:
In the '20s, a parenting guide cautioned Mom that a sitter might trundle her tender charge out on the town, so she could flirt on street corners. In the '40s, Newsweek reported that one veteran and his wife had hired a girl who turned out to be a dance-crazed “bobby-soxer” inviting friends over to party, while the toddler in her care teethed on marbles. Since then, the bad baby sitter's renown has only grown, as she's come to play a prominent role in urban legends, horror movies, pornography and even pop music, according to Miriam Forman-Brunell's new book “Babysitter: An American History.”
The bad baby sitter's a teenage girl, often dressed inappropriately, who is an unreliable scatterbrain, more interested in doing her nails or texting than the kids. When she's not glued to the TV, she's gabbing on the phone all night while eating Mom and Dad out of house and home. Or maybe she's sneaking her boyfriend in after the kids are asleep, or batting her eyelashes suggestively at Dad on the drive home. The bad baby sitter can be a threat not only to the children left in her care, but also to the very marriage of the parents she's working for. But as historian Forman-Brunell's research reveals, the archetype of the bad baby sitter has more to do with adults' fears about the changing nature of girlhood today — whether today is in 1945 or 1995 — than it does with the reality of girls caring for younger kids for pay.
More here.