well I know this, when giving a boring presentation everyone in the room has contempt for you, because during the speech/presentation you are a obstacle preventing them from getting on with and enjoying their lives. Then again there's always the chance of an angry mob or getting trampled.
Good point - a sleep-inducing presentation is a waste of time. Being boring is probably worse than looking stupid. Giving presentations is an act of bravery because when we stand up in front of others, we are revealing ourselves and all kinds of fears come into play. I don't think, however, that everyone in the room has contempt for you. Some of the audience will be grateful that it is not them up there speaking. Some of the audience will be generously trying to understand you, trying to figure out your message. The people that don't want to be there shouldn't be.
Yeah I know I was exaggerating but if you are in front of a crowd and nervous you are usually not thinking rationally about the other person's feelings. I know I do not speak for everyone but I am a bit of an over-thinker and often jump to the worst case scenario.