BEing able to hold one note doesn't equal the ability to hold many different notes, I also, if you would care to try READING what I said, didn't say she couldn't sing nor that she couldn't hold those notes. I said its possible she likes singing that way, or that she can't hold her notes.
A TRULY great voice can hold almost any note and will only use a note they can hold, plenty of people do it way to much as a style though and it mostly sounds completely stupid. Aguilera would be one who does it constantly throughout her whole range, but its perfectly obvious she can sing the same notes without warbling when she wants to.
Funbags, otherwise known as Mariah Carey holds notes in her middle range perfectly, everyone tarts on about her massive range, but her very upper and lower stuff is always warbled, always, because those harder ranges she can't hold very well. Decent singer obviously but also sings utter utter tosh.
As said, Lott seems like she can sing, but her first two things were generic turdpiles, the latest one is better "music" but still bland and dull lyrics, cliched bull that I could happily live out the rest of my days never hearing again.
She's hot, cute and pretty, but her music couldn't be more boring.