Come to think of it, is Cazador being a vampire lord supposed to even be a secret in the city? Or is it one of those open secrets like "capitalism bad" or "royalty are all parasites"? I seem to recall some banter from Gale that implied he knew before Astarion even mentioned his name.
I think it's a bit of a mixed bag. Gale knows of a vampire patriarch named Cazador Szarr, who is supposed to be very cruel. But in the conversation between him, Astarion and Wyll, the conclusion that this vampire lord is Astarion's master or a public figure of Baldur's Gate, is never drawn. The name doesn't ring a bell for Wyll at all. (Tangent: It is infuriating that this conversation doesn't play if you pick any of the boys as your Avatar.)
Astarion: Ever heard of a vampire called Cazador, Wyll?
(If it is known that Astarion is a vampire) Wyll: I don't think so. Why? Friend of yours?
(If it is not known that Astarion is a vampire) Wyll: Doesn't ring a bell. Why?
Gale: He's patriarch of the Szarr family. Nasty fellow, if the histories are accurate. Astarion: I imagine they are.
From Astarion and a note found in Cazador's palace we also know that Cazador is seen as just another noble by the upper crust of Baldur's Gate and that he is anxious to keep it that way and not have important people ask too many questions.
It starts at 30:35, timestamps don't like me today.
So, it seems to me, that Cazzy is generally perceived as an ordinary noble and seen as distinct from the notorious vampire lord, but that the vampire simps connect the dots and knock at his door. Of course this doesn't add up, as Cazador himself recruited at least two of his children from the bureaucracy of Baldur's Gate and Leon seems to have been well connected enough to know that Figaro does shady things and has the resources to pay him. It's probably all a bit mixed up with the EA background which seems to have been a bit different.
