Christina Aguilera has one of those voices that walks the line between 'powerful and emotive singing' and 'shouting like a drunk'.
Her early music created a fairly pleasant but unremarkable 'girl next door' image.
Then songs like 'Dirrty' and 'Can't Hold Us Down' showed that she was a fan of rumpo.
Christina also released a sensible jazz/blues album called 'Back To Basics'. It was a lot better than it had any right to be, but it's not exactly an easy listen.
On 'Bionic' she went back to not wearing many clothes and honking rather than singing and telling us how much she enjoys sexual intercourse and that sort of thing.
It was a bit of a mess and not many people liked it, which was a bit of a shame really as there were some good songs scattered throughout the 'project'.
Things improved for Christina in 2011 thanks to a role as a judge on The Voice, an 'authentic' 'alternative' to American Idol, etc etc etc, and the superb hit single 'Moves Like Jagger' with Voice co-coach Adam Levine.
But it all went tits up again when 'Xtina' released 'Lotus' in 2012, a lengthy warbleathon of bloated sex romps and over-egged Sia ballads.