Exactly! Scaring people on purpose (esp. when you know they don't want to be scared) is very mean spirited. Psychologically speaking, there's something radically wrong with her in the fact that she gets such a big kick out of doing that.
I forget who it was, but I read a while back that someone told producers to ask Ellen NOT to do that bit, and yet Ellen scared the shit of the guest anyway. What a sick mofo!