Aha, there's a name for this stupid way of talking...

From a BBC article about Australian Question Intonation:

The potential spread of vocal fry could be an interesting case study. The phenomenon sees the speaker use their larynx in such way that a lower creaking or rattling quality enters their voice. There has been a great deal of discussion about it in the last few years in the US, with Kim Kardashian and Lena Dunham - when acting in TV comedy Girls - cited as examples.

I'm glad that others have noticed this.

Particularly vain women on the telly talk like this (e.g. all the women in Made In Chelsea, if you ever happen to have the misfortune of being in the room while somebody is watching it) and my wife and a lot of her friends have adopted it.

Vocal fry is more or less the opposite of AQI where at least you can understand the words and you just have to guess whether it was a question or a statement. With vocal fry, the last couple of words in each sentence are usually nigh inaudible, which makes it really, really annoying as you have to keep asking them to repeat the last bit, or you just decide that anybody who talks like that doesn't have anything interesting to say anyway.