In today’s column, Why don’t British singers sound British when they sing? - The Straight Dope, I would like to correct Cecil on one minor point. Americans don’t say “liddle” for “little”. If there were a word “liddle”, it would differ, not in the consonant, but in the length of the first vowel. Two clearer examples are “rider” vs. “writer” and “ladder” vs. “latter”. Which is striking because vowel length is almost never a distinguishing feature in English. The consonant in each case is a tap of the roof of the mouth, or a near tap, with the tongue.
A propos his main point, I was once (probably around 1980) in a cafe in Strassbourg with a German friend when a pair came in and started singing American rock in a perfect American accent. I remarked on this and my friend claimed that they might not even speak English, but had learned to imitate American rockers. I was not able to confirm this.