I saw a documentary on it, though it include men on a sort of tour where they met with many gorgeous women of that nation. 10 US men to a 100 gorgeous native women. You have to look at the situation in those countries (such as Russia) where women out number men. Men do not have to even try and get a woman, if he isn't a drunk and already married, he's a keeper. So, their situation might be better as a mail-order bride.
I'm sure in some situations it can work out, the man gets some arm candy (or in the rarest of occasions, love) and the woman gets into the US easier. Though, I do see a big opportunity for abuse.