The thing with advertised tit size, is that cup sizes can be confusing. I'm not an expert on this, but I have seen women who claim to be D cup but look more like B to me. But you look at their bra label, and hey presto, they're not necessarily lying.
There's some equation I read somewhere that says 36B and 34D are the same. Or something like that. Maybe one of our female contributors can elucidate.