Every presenter has to deal with a difficult audience or audience member at one time or another. Professionals, however, because of topics or situations that are inherently uncomfortable, or because of mandated/resistant audience members, will face these audiences more frequently.
It can be difficult to get a resistant audience/member to resonate with your message, but if they leave angry, uninspired, unmotivated or unlikely to act on your call to action, you don't get the results you need or want.