"No candidate is good" is kind of a truism. I think it's safer to say that some candidates are less bad than others.
To put it in a medical perspective, pretty much every candidate has a serious case of the flu. Some go beyond that to emphysema or COPD, while some are terminal cancer patients.
Then you have guys like Jimmy McMillan who, in this analogy, are about 1/8th of a second from hitting the wood chipper at a dead sprint.