Do nannies help you???

I don't really play with nannies a whole lot, but with a set of twin toddlers and a set of newborn twins in a row I've given in lol
Anyways, she was working fine for a while.. Took the toddler out of the high chairs, cooked, fed them, played, took care of the babies, blah blah.. But when my sims went to sleep, she found her way to a single bed and just kept "spraying the monster under the bed" over and over. The babies crying next to her didn't stop her, and after my sim spoke to her she just went back to it. Fired her and got another, same thing happened.

Has this happened to anyone else? ;-;