Have you ever sat next to someone on Metro who was playing their ipod so loud that you could hear the F-WORD being repeated in a rap song for 20 minutes? I don’t think I am thin-skinned to think that is a bit much. The fact that the Metro is already noisy doesn’t make music leak OK. It makes it that much worse.
Obscene content is another matter, I’ll grant you. I do recall way back in the 1990s, in Boston, telling someone, “Excuse me, but there are kids on this train, and we can all hear your music.” I’ve heard a lot of earphone leakage in Washington, DC, but not so much obscene rap. You called the subway “Metro.” Are you in DC? Maybe it’s worse on some lines than others.