If someone has the balls to sneak into an empty seat, I say go for it. Very possibly the actual seat holder will show up and the encroacher will have to leave and return to his or her original seat or try to score another freebie. Either way, it doesn’t have to affect me one way or the other. Would I do it? Probably not, but I’m not a big rule breaker. I used to think I was, but most of my infractions created a lot of guilt, like cutting class or some equally innocuous action. So that’s my opinion, for what it’s worth.