The same goes for heckling in Legislatures. Sure, it makes for great theatre and yeah, it throws off your opponents, but so do taunts on the schoolyard.
We elect leaders to set the example. The standard they must judge themselves by is "would I want to see anyone I represent act in the same way I do?"
Deflect all you want, hide behind "politics is a blood sport" all you want, but remember this - leaders don't make excuses.