Astronomers report planet better than Earth!

[stevebowers]

This is going to be a difficult one. I expect that a lot of planets might look hospitable from a distance, but they'll be hell-holes close up. A lifeless planet would have nothing to breathe, and a life-bearing planet might have dangerous organisms (or at the least, inedible ones). So even if astronomers were to announce a hospitable world there would be plenty of room for doubt.