What is deceptive about it? They say openly for whom they are and what are their beliefs. I would say that progressive Episcopalians or liberal Reform Jews are deceptive, they claim to be religious and they promote libertinism.
One flaw of Jews for Jesus is that they are simply Protestants and they are not aware of it.
Flaw, or fraud? It is a stupid marketing gimmick. Just say Christians for Christ, as other missionaries do.
I doubt they would see it that way. And perhaps many would say that their Jewish culture, and their faith in Judaism led them to see that the messiah is Jesus. I don't know if they would welcome removing Judaism entirely from their practice of Christianity. I believe that many combine the two faiths together. But in the end, yes, they would acknowledge that they are Christians and that Jesus is their messiah and savior.