This didn’t happen to me, but on Saturday my friend Rui went to the U-Bahn station and bought a ticket from one of the vending machines.
Next to him was an American woman who was trying to buy a ticket, but couldn’t understand the machine, so she turned to him and asked, “Do you speak English?”
The answer to this was in the affirmative, and was followed by the woman pointing at something on the screen and asking, “What does this say?”
To which Rui said, “I don’t speak German–I only speak English.”
He did point out that one of the options on the display was to change the language.
I suppose you’ll find an abundance of German speakers in Germany, but I find this story amusing.