I've never crashed anything formal, just those house party kind of things where a friend of a friend of a friend invites me.  I've never had anything I've hosted technically crashed.  Occasionally an invited guest will bring another guest unannounced but was never a big deal.  I had hubby's 40th bday party at a formal reception hall.  In the next room, there was a wedding reception.  Bryant's uncle, who is a raging alcoholic, wandered into the other room after using the restrooms (between the two rooms).  Once we noticed he was missing (and panic ensued). hubby found him dancing his butt off with the mother of the groom lol!  I have been at other events that have been crashed and a few times the results were disastrous.

'And those seen dancing were thought to be insane by those who could not hear the musicNietzsche