In Sade´s music, I would translate into "bom de lábia/enganador", labioso (conquistador barato) [here, in an aproving way, given the musical contextualization - she is falling for him...]
You could say that he is a "enganador" (a guy that "played her" making her think that she was the only one) A "malandro" indeed, in the sense of living some kind of double life or cheating on someone else (or everyone else he meets on the night. Fact is, she senses, since she says "no need to ask", or perhaps she hopes to change him somehow.
Or feels he is very much of her same ilk (if so, then "seu malandro/malandrinho conquistador" ) com sua voz doce, etc... might be the case as well.
The way she sings, she is almost saying "I can resist anything except temptation." (kinda - I know, I know, but I just can´t help it.)