That's interesting. Yeah, it's the wrong era dialect for that babysitter (is she originally from Kansas or OK I wonder?)
Both sides of my family came out of the dustbowl, and while I agree that plainspeaking is the way they spoke, it in no way meant that someone was trustworthy. My crazy aunt (the one whose personality resembles LS's) spoke that way too. She was a smart but cagey woman (who could be vicious verbally, rarely physically though).
I think the babysitter was on video, but can't remember for sure. My parents never would have used the word "beat" no matter how the "spanking" went, btw. They used "come down on someone" to mean a variety of negative effects for the object of the come-down.
My dad used "give a skinning" not "get a beating." He also said "wail the tar out of." My mom and grandma, appropriately, said "get a switch on."
Anyway, I'm thinking babysitter introduced the idea of physical punishment in her phrasing. I am biting my tongue enough now, I better stop.