figured out why their accents sound fake

After living for so long in the States, the girls have taken on the American way of speaking, which means running their words together and speaking at the back of the throat.

The English way of speaking has people use the front of their mouths (teeth and tongue) to pronounce words which mean there's a tiny bit of space between words and different syllables accented (upward inflection) toward the end of sentence.

Most Americans tend to slur their speech so it's almost sing-songy and no real break between words and a downward deflection. Most americans don't really enunciate words correctly making them sound less than articulate.

When you put the two together, it sounds like Americans trying to do an English accent, but when the girls do it, it sounds bad because they're putting American sounds into their English way of speaking.

Try it out if you don't believe me. If you're American, try speaking but pull your tongue back a bit and use the front of it more than the back and pronounce every syllable in a word and keep your teeth together and lips slightly apart. If you're English, reverse it.