I can understand tight finances, but that doesn't excuse half assign childcare arrangements. There are many resources, from police checks to online ratings that you can search to get references.
Ive heard horror stories about nannies too, from depleting the liquor cabinet to inviting their boyfriends over for nooners while the kids play in the basement.
still, if you have more than one kid, a nanny is actually cheaper than daycare.
We are lucky to have our parents around, who drop in or even stay around all day to check on the kids. So far, we are very happy with our nanny. She's a keeper.