Bach's Cantata #42 (IIRC) casts Jews in an undesirable light.  I recall
an album booklet (may have been Telefunken) where "Juden" in the original
German became (appropriately) "Juifs" in French and (editorially) "Enemies"
in English.  A shame because the music is gorgeous.

Another instance of overt anti-semitism to watch out for is in Metastasio's
Passion Play (lines include "Does Hebrew cruely know no bounds?" and "They
will pay for what they've done to their king!").

Aaron J.  Rabushka, who often runs into trouble in Jewish communities for
being slow to jump on alleged anti-semitism where they think they see it
[log in to unmask]
http://www.cowtown.net/users/arabushk/