Jesse Jackson had said things that were perceived as anti-semitic.
That's being kind. Jesse Jackson referred to New York City as "H----town", while actively receiving the support of Louis Farrakhan. This was in his 1984 campaign.
What qualifications did Jackson have that suggested he was up to the office of the Presidency? I find that one hard to come up with. I would ask people here what qualifications for the Presidency did Jesse Jackson had that Pat Robertson did not have? They both ran in 1988; why does Robertson (who is, indeed a jerk) get flamed while Jackson gets a pass?