I think it is important for us to distinguish between the pragmatic left and the radical left. While my views in this forum are no secret, I don't believe that everyone left of center (in the Israel/Arab conflict) is a "traitor", "self hating", wishes Israel ill will, etc. I do TRULY believe that there are leftist who believe that their views or solutions to the conflict are what is best for Israel. In my humble opinion, here are some major differences:
1) pragmatic left: does not believe that Israel is the villain in this conflict, while the Arabs are white and blameless (although they don't believe Israel is blameless either)
radical left: believes Israeli is the sole villain in this conflict and that the Arabs are virgin white and 100% peace loving people that are only reacting to evil Israel (specifically the evil Zionists)
2) pragmatic left: is willing to compromise with the Arabs and give away yet more territory (even give up access to some holy sites, which are a bedrock to Jewish holiness and identity) not because it is good for the Arabs, but because it is good for Israel (at least they believe it is good for Israel)
radical left: believe the Arabs deserve it all, the whole territory from the Mediterranean to the Joran, from Syria to Egypt REALLY belongs to the Arabs and the Jews are really foreigners in this land, but as a "good will" gesture they will let Israel continue to exist on as minimal a piece of land as possible (or call for a "one democratic state" solution)
3) pragmatic left: condemn boycotts that are blanketly aimed at ALL Israel/is (even if some, but not all, of them are in favor of boycotting products from Judea and Samaria)
radical left: enthusiastically join boycotts with those who call for boycotting all Israeli professors, products, etc.
4) pragmatic left: condemn those who refuse IDF service (even those who refuse to serve in the "territories" alone) and continue to serve themselves
radical left: call on EVERYONE to refuse ALL kinds of IDF service, no matter where and in what capacity
5) pragmatic left: ready to defend the top brass in the IDF, as well as other politicians, who are threatened with being tried for war crimes for operations, such as Cast Lead. This does not mean they are against investigating any wrongs committed in operations that might have been done by mistake or intentionally to make the IDF a better and more humane military than they are now
radical left: basically believe the IDF can never do any right and enthusiastically join Israel's enemies in calling for IDF officers and other politicians to be tried for war crimes, as well as knee-jerkingly condemning any operation by the IDF against threats to Israel's security, whether preventative or as retaliation
I am sure I have not covered all the differences, but these are the core. So, no, I don't believe all leftists have it in for Israel.