I have never been at the theatre when I have witnessed something like this happening. But, I have read a lot of interviews with actors who play the bad guy in children's shows like any Disney on Broadway show. They say that they they look at it as a compliment because by getting the audience to boo it shows that they did their job to scar/annoy the children in the audience.
And, keep in mind. In those shows there are usually more children in the audience then there are adults. So, that is why there would be more boos then cheering.
"If you try to shag my husband while I am still alive, I will shove the art of motorcycle maintenance up your rancid little Cu**. That's a good dear"
Tom Stoppard's Rock N Roll