I have a feeling there are about 20 million Japanese people logging on to their version of YouTube, laughing hysterically at our pathetic attempts to do karaoke in Japanese.Let me add that the accent might be coming from non English speaking countries (about 80 % of the world (Chinese are throwing off the numbers here)). I have been speaking English for at least 35 years and I still cannot get rid of my French accent when speaking English: wait till I sing, it will not go away .
Some people have a very good ear like Celine Dion (sorry to bring her up) who has a strong French accent when she speaks but sounds anglophone (a local term in Quebec) when she sings. Some Spanish singers are also the same where the Spanish accent comes out in regular conversation but sounds American when singing. Most non English people when singing will try to imitate the English accent but it is no a given. See how often Chinese are laughingstock on the internet when trying to sing in English. An accent is very difficult to hide unless you learn the second language young enough.
Something is certain the American culture is everywhere and I am enjoying it, but paying attention to the other cultures make life quite interesting.
Marc
There are always going to be cultures that simply were not raised with the peculiar sounds we make in English. So even when they sing American songs, their native accents come through -- strongly. Mostly, though, I'm referring to those people from countries where American phonetics aren't so distant from their own. I've travelled around a bit, and I've heard Germans, Italians, French, Israelis, and a variety of Spanish speakers sing in English extremely well, despite the fact that they can barely speak the language.
Here's something that just occurred to me: there's probably a correlation between one's ability to sing well and one's ability to imitate other accents. I've noticed that people who have an ear for music are also very good at speaking foreign languages.