Anybody arguing that some of these girls might have heard of Joe Millionaire 1 would argue that they might have heard about it through the internet, not from TV.
Such a person would also argue that they did not need to be actively involved in discussing the show in any type of forum such as this, but could merely hear the name and the premise of the first show in passing, and remember it when casting for a show with a similar "initial premise". By "initial premise" I mean the fact that a certain number of women will try to win the the heart of one seemingly rich man, in an American TV show. Such a person would then argue that a girl that had read JM1 info on the internet need not know the real name of the American TV show she is casting for, nor the ultimate premise (the man is very rich), to guess which direction the show would be headed in.
What a pain in the rear such a person would be though! Just watch the show and enjoy it! (This last part is directed entirely at such a person, myself.)