Meh, I don't know why everyone gets bent outta shape about a smashed guitar. It's only rock n roll.
That being said, it can't be the staged, fake BS. Gotta be the real deal energy of the show moment. I've played shows that were awesome, ended with a bang and I certainly felt it in me to take it out on my guitar. It's a primal thing when it's genuine. You know... emotion...like music should have. That being said, I've never smashed a guitar. I can't afford it.