Actually it's not so easy... Some women could result offended if you call them "signora"; because actually we use it for married women and old ones; so if a woman that it's not married gets called "signora" could think you are claiming that she's old... And we all know no woman wants to hear that... Ahahah
The meaning of the sentence in English is that the alternative woman is a trollop, but the translation into Italian, whilst apparently straightforward, makes me wonder if it would be understood. I translated it to be -A woman is not always called a lady. 'Una donna è non sempre chiamato una signora.' I knew it would be wrong for Duo, but is it?