It is never fun of there are hostile people in your audience. But what can you do? Here are some good ideas.
http://www.thereluctantspeakersclub.com/blog/2011/11/deal-with-negative-audiences-or-trolls/
We all know about the pain of public speaking. Here are some ideas for coping with the pain.
http://www.chron.com/business/article/Q-amp-A-Public-speaking-without-the-pain-2277432.php
But despite the pain we should all be thankful.