Hillary has made a number of unfortunate statements lately, the recent one about RFK being the most egregious. Sometimes this kind of thing is the result of groupthink. When a group of people attempt to make a decision or choose a plan of action, loyalty to the group may trump concern for a good outcome. Individual members who might have dissenting views tend to bite their tongues. In other cases, the members of the group are chosen on the basis of their loyalty, and diverse opinions are unlikely to surface. Groupthink has been blamed for the Bay of Pigs Invasion fiasco and other bad governmental decisions.
Now that Hillary is facing such adversity, the circumstances seem ripe for groupthink. To keep going and remain optimistic, it would be natural to surround yourself with loyal, like-minded people. Listening to devil's advocates would be more difficult. The problem, of course, is that loyalists will not tell you that a phrase like "hard-working white people" is a bad idea or that the mention of presidential assassination could be offensive. 
Ironically, President Bill Clinton sought out the Republican David Gergen as an advisor, a move that increased the likelihood of diverse viewpoints. This must be a difficult time within the Clinton campaign, but if Hillary wants to avoid tarnishing her image any further, it will be important to listen to diverse viewpoints. If she hasn't already, Hillary should find herself a Gergen.