I have several jewish friends who are dumb, illiterate and boring, so I guess they are just people with good qualities and bad ones.
It is very standard to qualify people from certain regions/cultures/countries based in a "predominant characteristic" that sometimes has not much to do with the reality but for some reason is the general perception (which we might call reality

)
When i hear the term "jew" specially when being said in a despective manner (is it always "jew" a despective way of saying jewish? If so I need to apologize because i didnt know) I think of cheap. Jewish all over the world have become known for its "ability" to make fortunes. I see one common factor among people who make money: They are not spenders (ie, they are cheap). Why wear a panerai when u can buy a casio for 50 bucks? Why wear a Brioni when you can buy a nice old navy shirt?
For some reason, right or wrong, jewish ,and the fact that they MAKE money, are seen like people who ask themself those questions everyday, therefore they are cheap.
All my jewish friends make that kind of jokes and they do think jewish are cheap. There is a region here in Dominican republic known for the commercial "abilities" oif its inhabitantants. he place is called bani and most grocery stores in Santo Domingo belongs to them. Every single joke that you've heard about cheap people in Dominican Republic involves a banilejo (a person from bani) or a jewish, and the jewish cmmunity here is really small.