Take a look at at this video, it is a rather famous commercial video for an English school.
If you speak English that’s very clear what the problem is as soon as the music starts. If the family understood the words at all, they would clearly see that this is absolutely NOT a song for the family.
I think in non native English speaking countries, sometime we can see this kind of situation. For example at a HIPHOP dance school. In HIPHOP culture its common to see strong lyrics and some can be very violent and sexual. This kind of material is not for kids. But in many HIPHOP schools with very young students have their kids singing and dancing to this kind of music. This would not happen in an all English speaking environment and even in a non-english speaking environment we should be wary of situations like this.
As Japan is getting more international I believe it’s important that we at least learn what words are taboo in certain situations. Even if it was just humming if the listener knows the song it could send the wrong message.