My best friend (in UK) was a nanny for years, she loved it & loved the children, but had a real horror story to tell about a friend of hers. This friend (let's call her "Barb")and my friend ("Amy") took a job together once. Turns out, "Barb" was an absolute brute-she used to force-feed the kids and when one of them vomited, Barb made her EAT IT. She called them names, pushed them around, etc...."Amy" had always been very friendly with this girl, and thought she would have no problem leaving "Barb" with her own children when she had them-she told me that day with "Barb" scared her to death. That's a large part of the reason why "Amy" became a nanny in the first place-at least with her, she knew the children would be safe.
This is why I will never, ever, use daycare or a nanny.