They are evil, because that is what they were created to be. Morgoth made orcs for the sole purpose of having an army of evil minions, basically. Of course, nothing is beyond redemption (besides osama). I think that even orcs could be good, but I also think that they would resist the attempt. Also, I dont think all elves are good. They are a "pure" race, but not without faults. Put this question down to ask Tolkien once you go to heaven.
