I just googled and got an article about a family that just learned that they're getting a makeover. So the ABC producers call them to notify them before hand..
http://the.honoluluadvertiser.com/article/2007/Jun/06/br/br0549823671.html
(ok, nevermind...it doesn't say they were called I read it wrong... I think I heard one time that they tell the families beforehand to be prepared just in case they show up. I guess that's why the families are always dressed and ready. I am not sure though)
And what's wrong w/the girl in the picture having a mic pack? They have to talk to the families anyway so they would mic them so we can hear them...