I've been poking around Greataupair.com, looking into the ins and outs of hiring live-in help. In the sidebar, there was a link to an item which I had not noticed before; Au Pair Scam Warning:

Do not send cash, Western Union or MoneyGram payments to aupairs in Ghana, Cameroon or other developing nations.

We have had several reports of families being scammed by people posing as an aupair or nanny and requesting that families send money via Western Union, MoneyGram or cash for airfare or other needs so that the candidate could meet the host family.

Schemes may be elaborate, involving supposed travel agents, professors, deans, parents and other false references. Verify the IP addresses of emails you receive from all references to make sure they originate from the place of work or country where the reference supposedly lives.

I had already concluded that hiring from overseas on my own without the assistance of an agency was something I was not willing to take on. I must admit the possibility of being scammed did not enter into my ruminations.