From wikipadedia-
"On the overall power of the song, Jagger continued in Rolling Stone: "It has a very hypnotic groove, a samba, which has a tremendous hypnotic power, rather like good dance music. It doesn't speed up or slow down. It keeps this constant groove. Plus, the actual samba rhythm is a great one to sing on, but it is also got some other suggestions in it, an undercurrent of being primitive—because it is a primitive African, South American, Afro-whatever-you-call-that rhythm (candomblé). So to white people, it has a very sinister thing about it. But forgetting the cultural colors, it is a very good vehicle for producing a powerful piece. It becomes less pretentious because it is a very unpretentious groove. If it had been done as a ballad, it wouldn't have been as good."[1]"
Well, if it's samba, that pretty much confirms it for their short dance for me. It's doesn't really fit with the wholesome image of V/M though, does it?