I emceed a concert at a folk camp once, and I didn't know very many of the performers. I decided to tell outrageous lies about every performer, and I suppose most of the lies had a negative tone...but I thought it was just in fun. It didn't go over. Since then, I've made only positive comments about performers when I emcee, and I make a point to learn a little bit about every performer, or ask the performer questions if I don't know.
Nowadays, people like my performance when I emcee.

-Joe-