I'm sort of saying that B & C (from what I gather) make a considerable pretense about being 'artists', 'vocalists', 'divas', etc.... in an attempt to play down their blatant use of soft-core porn/pop culture approaches to selling their product; all their posing as musical artists sort of makes me queasy (completely apart from their music itself which I detest, but that is separate from my critique of their self-marketing).
The TATU gals are just (it seems to me) a bit more honest and forthright about their use of sexuality to market themselves, even going so far as to admit that they're not really lesbians but just pretending in order to be popular. True, they're being honest about a deception, but there appears to be some convolouted sincerity in that nonetheless. I haven't heard any of their music (I imagine that it would be as unappetizing as B & C, but maybe slightly less so due to the fact that I don't speak Russian and therefore wouldn't understand the lyrics).

Along these lines, I found Madonna's use of sexualtiy in the effort of self-promotion to be less objectionable (than B or C) too. Like Danni BTW, I think Madonna's sexier now than she was 10 years ago incidentally.
And the fact that either of the TATU girls is (IMHO) a dozen times easier on the eyes (especially the redhead) than B or C is something in and of itself.