My husband and I were in the subway in Buenos Aires a few weeks ago. There seems to be a certain tactic that robbers use in the subways.
They first want you to go first either in the train or an escalator. One robber is in the front while the other robber is behind you.
I was about to go into the train and one very well dressed man told me to go first. He looked to my left at another man and this man too told me to go first. Somehow I ended up in the train first and my husband was caught between two men. When my husband got into the train the other man who was on my left suddenly left the train saying it was the wrong train. We did not loose much since we never carry much with us. They only got a few dollars from us.
Our friend too almost got robbed in a similar manner. However when my friend got the woman to get in the train first that woman quickly left the train.
So be careful when traveling to Buenos Aires by subway.